You may be asked to do this when apps or updates are having a hard time installing on the phone.
1. Swipe up on the Home screen (1) and then select My Files (2).
2. Select Downloads.
3. Long-press any files to select them (1) (make sure to select all of them) and then select Delete (2).
4. Select Move to Trash (1) and then Back (2).
5. Select Installation files and follow steps 3 and 4 to delete any files here.
6. Select Trash (1) and then select the three dot menu next to Edit (2)
7. Select Empty (1) and then Empty Trash (2).
8. Close My Files.