Go to Apps and click it.
Scroll to File Commander and click it.
Click Internal Storage.
A list of the aps on your tv box will appear. Scroll to Download and click the three dots on the right side.
Click Delete from the pop up menu that’s appeared.
Click the box beside Delete Permanently so that a checkmark appears in it.
Done! Click back or escape to return to the main screen.
If you want to clear other old files, you can in the same way. Do not delete Android, RetroX or Game Data.