Tap [User Box].
Tap [System] - [Bulletin].
Select the desired User Box, then tap [Open].
If the box is password protected, tap [Open] and enter the password.
You can also open the desired User Box by tapping it twice.
Set the desired operation.
Select a file, then tap [Delete]. The file is deleted. You can select multiple files and delete them simultaneously. Check the file details, then tap [Yes].
Tap [Details..], and you will be able to preview the file.
To enlarge/reduce the preview image, tap [View Page].