My galaxy tab A6 haven't storage how to clear the problem

From Samsung directly:

https://www.samsung.com/us/support/answe...

Quote for that site for longetivty sake:

The My Files app stores every file you have on your phone or tablet. It's like the File Explorer on a PC or Finder on Mac, where you can easily view and move photos, videos, music, documents, and more.

1. Navigate to and open the My Files app. It's usually in the Samsung folder.
2. Select your desired file category. You can choose between Images, Videos, Music, Documents, Downloads, Installation files, Compressed, and Favorites.
3. If needed, select any additional folders that contain your desired files (i.e. Screenshots, etc.). Touch and hold the file(s) or folder(s) you want to move.
4. Tap Copy to create a copy of the files in a different storage area. Or, tap Move to completely remove the file and move it to a new location.
5.  Next, navigate to and select your desired destination:
   • Internal storage: Move the file(s) or folder(s) to a different location within the same internal storage.
   • SD card: If you have a microSD card inserted, tap SD card, and then select the destination location. Please be aware that apps cannot be moved to the SD card using My Files. You will need to use another method.
   • Google Drive: If prompted, sign into your Google account to access your Google Drive. You can transfer files to and from the cloud.
   • OneDrive: Log into your Microsoft account and grant permissions for MyFiles to access the OneDrive cloud.
6. Once you've found where you want to put the file, tap Move here or tap Copy here.