If your phone memory is getting full, move files to a memory card or delete unnecessary files.
Transfer files to a memory card
To move photos from your phone memory to a memory card, tap Files > Images. Press and hold the photo you want to move, and tap more_vert > Move to > SD card.
To move documents and files, tap Files > Documents & Other. Tap keyboard_arrow_down next to the file name, and tap Move to SD card.