Whenever I delete a book from my list, it comes back when I log in

I support staff in our library. We use Windows 7 (64-bit) on "standard" HP systems - one employee has a Digital Editions account that always says there's an update at login but never actually updates (but prompts again at next login) - and whenever she deletes a book from her downloaded collection it shows up next time she logs in with my her Digital Editions account.  Also, sometimes if she downloads a book from our library it shows up in her checked out list 3 to 5 times. Also - if she logs into a completely different PC, similar things happen; seems like it's never exactly the same, but similar (e.g. some or all books that are deleted, come back at next login) ... I suspect my Adobe Digital Editions profile may be whacked.  Is there any way to reset it (wipe it out and start fresh)?