Deep cleaning Android manually: removing system junk

A noticeable slowdown of the smartphone and rapid filling of the internal memory are often caused by the accumulation of hidden caches and residual files of deleted applications that standard cleaners simply do not see.

Unlike automatic utilities that can mistakenly delete the necessary data or simply show a beautiful animation of freeing gigabytes, the manual method gives complete control over the file system. You know exactly what you are deleting and understand the nature of each file. This approach requires care, but guarantees results where bots are powerless.

Before proceeding with deletion, it is important to understand the structure of data storage in Android. The system divides memory into the system partition and user storage, where the bulk of garbage accumulates. We will work primarily with user memory, using a standard file manager or advanced tools for accessing hidden directories.

Preparing a file manager and accessing hidden folders

For high-quality cleaning, the standard explorer that comes with the phone is often not enough. It hides system folders and doesn't show directory sizes, making it difficult to find the culprits that are filling up your memory. It is recommended to install a specialized file manager, for example Files by Google, Solid Explorer or FX File Explorer.

After installing the application, you must activate the display of hidden files. Usually this option is located in the settings of the Explorer itself and is called “Show hidden files” or “Show hidden files”. Without this step, you will not be able to see folders starting with a dot, which are often used by applications to store temporary data and ad cache.

Pay attention to permissions. In modern versions Android 11 and newer, access to the folder Android/data and Android/obb is limited by the security system. To view their contents, the file manager will need special permission, which is requested the first time you try to enter these directories. Do not ignore this request, otherwise the cleaning will be incomplete.

⚠️ Attention: Do not delete files from system folders located in the root of the disk outside the directory /sdcard or /storage/emulated/0if you are not 100% sure of their purpose. This can lead to unstable operation of the system.

Cleaning the application cache and residual files

The largest amount of garbage is generated by social networks and messengers. Applications like Telegram, WhatsApp i VK save every media file you watch to disk, even if you already saw it a month ago. Simply deleting a chat does not erase this data from the phone’s memory; it remains in hidden caches.

To clear it, go to the phone settings, section Applications, and select a heavy application. Inside the menu, find the “Storage” or “Memory” item. Here you will see two buttons: “Clear cache” and “Clear data”. The first deletes temporary files, the second resets the application to factory settings, deleting logins and correspondence.

Residual files are often located in folders with the names of deleted apps. If you uninstalled a game or utility a week ago, check the root of your internal memory for folders with similar names. Developers do not always delete their directories during uninstallation, leaving behind logs and configuration files.

• 🗑️ Folders .thumbnails in the directory DCIM contain thumbnails of your gallery and can take up gigabytes of space.
• 📂 The directory Download is often filled with installation files .apkthat are no longer needed after installing the apps.
• 📝 Debugging logs in folders log or logs from old ones applications that you have not used for a long time.

Analysis of the Android folder and removing garbage from data and obb

The directory Android is the heart of user data, but also the main garbage collector. Inside it there are two key folders: data and obb. The first stores application data, settings and cache, the second stores additional files for games, such as textures and maps.

When deleting a game through the standard interface, only the application itself is often deleted, and heavy files from the folder obb remain dead weight. Go to the path Internal memory/Android/obb and carefully examine the list of folders. If you see a directory with the name of a deleted game (often a set of characters like com.rockstargames.gtasa), you can safely delete it.

With the folder data you need to be careful. Inside it are subfolders with the names of application packages. You should only delete content here for apps that you have already deleted, or if you want to reset a specific application completely. Deleting the folder of a running application will result in the loss of progress in games or settings in utilities.

Folder type	Location	What can be deleted	Risk of data loss
obb	/Android/obb/	Deleted folders games	Low (for remote games only)
data	/Android/data/	Deleted application cache	High (resetting active applications)
cache	/Android/data/[package]/cache	Temporary files inside	No (the files will be restored)

Why is the .thumbnails folder bloated?

The system creates thumbnails for each photo and video in the gallery for a quick preview. With a large number of media files, this cache can grow to 5-10 GB. A safe solution is to periodically delete the contents of this folder; the system will create it again if necessary.

Manual deletion of duplicates and forgotten downloads

Over the years of using a smartphone, hundreds of files accumulate in the folder, the existence of which you forgot. These are old versions of apps, PDF documents, images from browsers and installation packages. By default, browsers save everything downloaded here, and there is no automatic cleaning there. Download Hundreds of files accumulate that you forgot existed. These are old versions of apps, PDF documents, images from browsers and installation packages. By default, browsers save everything downloaded here, and there is no automatic cleaning there.

Duplicate photos are another problem. When synchronizing with cloud services or accidentally resaving from messengers, the same picture can be stored in memory in several copies with different names. Searching for them manually takes a long time, but you can sort files by size in the file manager and delete the heaviest duplicates.

Pay special attention to files with the extension .apk. These are application installation packages. After successful installation of the app, they become useless ballast. Find all files .apk in the storage (many managers have a filter by file type) and ruthlessly delete them if you do not plan to transfer them to another device.

⚠️ Attention: Before bulk deleting files from the “Downloads” folder, check for important documents, tickets or receipts there. Users often store necessary information there for years, forgetting about its location.

Cleaning through developer mode and ADB (for advanced)

For those who want to achieve maximum results, it is possible to use USB debugging and console ADB (Android Debug Bridge). This method allows you to delete the system cache and files that are not accessible to the average user through the phone interface. You will need a computer and ADB drivers installed.

First you need to activate developer mode on your phone. Go to Settings → About phone and click 7 times on the “Build number” item. After this, a new section “For Developers” will appear in the settings menu, where you need to enable “USB Debugging.”

Connect your phone to the computer and launch the command line. To clear the cache of all applications with one command, you can use the following script. Be extremely careful when entering commands, as they are executed instantly and without additional confirmation.

adb shell pm trim-caches 999999999

This command instructs the system to trim the cache of all applications, trying to free the specified number of bytes (in this case, almost everything that can be safely deleted). This is a deeper clean than the standard button in the settings, as it affects the system services cache.

What cannot be deleted manually: critical system files

When cleaning manually, it’s easy to get carried away and remove something unnecessary. There are a number of files and folders that are strictly prohibited from being touched unless you want to turn your smartphone into a “brick” or lose personal data forever. The Android system protects them for a reason.

Never delete files with the extension .xml or .db from system folders if you do not know exactly their purpose. These are databases and configuration files. Also avoid deleting folders with manufacturer names (for example, Samsung, Xiaomi, MIUI) in the root of memory, where themes and system shell settings are stored.

File .nomedia is a special marker that tells the gallery to ignore this folder. If you delete it from the system directories, your gallery may begin to index thousands of service icons and interface pictures, which will cause the phone to freeze when opening a photo.

• 🚫 The folder system and its subdirectories contain operating system files.
• 🚫 Files vendor and product in root access - drivers and specific software.
• 🚫 Folder Android/media with caution - offline maps and music may be there.

⚠️ Attention: Shell interfaces (MIUI, OneUI, ColorOS) are constantly changing. Some folder locations may vary. If you are in doubt about the purpose of the file, it is better to skip it than to risk the functionality of the device.

What to do if you deleted unnecessary things?

If after deleting the files the phone starts to work incorrectly, try rebooting into safe mode. If the problem is in the settings, resetting to factory settings will help, but this will delete all data. Always make a backup copy before deep cleaning.

Preventing memory clog in the future

Manual cleaning is a one-time measure, but in order not to return to it every month, you need to change your smartphone usage habits. Set up automatic cleaning in messengers. In Telegram, for example, you can set the cache to be automatically deleted after 3 days or a week in the “Data and Memory” settings.

Use cloud storage for photos and videos. Services like Google Photos or Yandex.Disk allow you to store originals in the cloud, freeing up space on your device, leaving only compressed copies for quick viewing. This is the most effective way to deal with lack of space in the long term.

Regularly check the list of installed applications. Remove those you haven't used for more than a month. We often forget about games we played once, or utilities that turned out to be useless. Each such application takes up space not only with its installation file, but also with an ever-growing cache.

Is it safe to delete the .thumbnails folder?

Yes, it is safe. The system will create it again the next time you open the gallery. However, for the first time, the gallery may take a little longer to load until the thumbnails are recreated.

Is it possible to delete files from the Android/data folder on Android 11+?

The standard Explorer may not give access. Use third-party file managers that support SAF (Storage Access Framework) or connect your phone to a PC to delete files from this directory.

Why is the space not freed up after cleaning?

You may have cleared only the cache, not the data, or deleted files in the trash. Check the Trash folder in the gallery and file manager - files are often stored there for another 30 days before being completely deleted.

Do you need to clear the system application cache?

The system application cache (for example, Google Play Services) can be cleared; this will not delete your accounts, but it will reset some temporary settings. Do this only if there are obvious problems with the system.

How to find the largest files on your phone?

Most modern file managers have a sorting function by size. Select sorting “By size (descending)” to immediately see the largest files at the beginning of the list.