You can erase all files in the selected folder.
Press
(folder) to return to the folder window before erasing the files and select a folder from which all files are to be erased, and then go to the menu window.
PLAY/STOP・ENTER.

“Erase All?” appears on the display.
or
+ to select “YES,” and then press
PLAY/STOP・ENTER.
(stop) to exit the menu mode.
PLAY/STOP・ENTER.