1. Click the nearest application key in the lower left corner of the screen (that is, the touch key on the left side of the only physical key on the screen)-click the circle icon in the lower left corner-click the end icon on the right side of the application or end all to close the background running program.

2. Uninstall the self-installed application.

3. Clear the Internet cache of the mobile phone: browser-menu key (three dot icons in the upper right corner)-Settings-Privacy Security-Privacy-Delete Personal Data.

4. Clear the recorded incoming calls, text messages, etc.

5. If the mobile phone supports inserting an external sd card, just insert the SD card and then transfer the file to the SD card.