At this point, if the currently-selected storage device is an external storage attached to your smartphone, a dedicated screen may open to prompt you to select a file and delete it from that screen.
The check mark is displayed to the right of the file or folder.
You can select several files/folders.
To select all displayed files/folders, operate as follows:
(1) Tap the spinner (triangle) to the lower right of the selected item number displayed in the upper part of the screen.
(2) Tap [Select all] from the dropdown list.
Deletion of the file/folder starts.
When deletion is complete, tap [OK] to return to the file/folder list screen.