Also readers can refer to some other ways to regain storage space on Android devices here.
First open the Photos app on your Android device, then swipe to open the menu in the left pane. Here you will see the option called " Free up space ".
After you click on the option, the system will search all files that have been backed up. This process can take several seconds to several minutes, depending on your device speed and the number of files.
Once the files are found, on your Android device's screen will display a window containing the number of files and options to delete those files. In the example below is 134 files.
After selecting the Remove option, on the device screen will display the process of deleting files. When the process is finished, a new message will appear at the bottom of the screen informing you how much free space has been freed.
Good luck!