Deleting Files

In the File Management page, click (more) on the left of the file to be deleted, and click [Delete].
Clicking [Confirm] in the pop-up confirmation window.
The file is deleted, and a message at the upper right corner of the page will appear and indicate that the file has been deleted successfully. Then the file disappears from the file list.

What is the difference between returning a file and deleting a file?

Returning a file removes that version of the file. Deleting a file does not change the version number.