Delete from Elvis
From MTG Wiki
Elvis does not have a trash can or a mechanism for restoring files that were deleted accidentally. To prevent problems, most users will not be able to delete files from Elvis.
Here’s what you can do instead:
If the file is already in a dossier in Content Station, delete it there first. Open Elvis. Click “browse” to see the top-level folders. One of them is called “Files to be deleted.” Move the file from its current location into that folder.
Admins will periodically empty both that folder and the Content Station trash can. This will be done regularly and without warning.