How do I delete Cloud Sync files?

I have found something that appears to work.  Go into File Explorer then to the My Digital Editions folder.  Go through all the subfolders and delete all the Cloudsync subfolders (there are four:  You will find Cloudsync under My Digital Editions, then three others:  Under Annotations, Manifest, and Thumbnails).  After I deleted these four Cloudsync subfolders I found that Adobe Digital Editions program worked fine and I no longer have books showing up in my Library that I did not put there.  I also check to see that any books I delete from my Library are no longer in any of the subfolders under the My Digital Editions folder.  If you accidently delete a subfolder that prevents Adobe Digital Editions from working properly, remove and reinstall Adobe Digital Editions and  start over.

I have found that if I try to "return/delete" a library book before it has expire then it cloud syncs again.  However, if I wait until it has expired before deleting it then it stays deleted.

I have the exact same issue. It's ridiculous. I read several newspapers through my local library on ADE, and every single issue I ever borrowed just keeps reappearing in my library, no matter what I try. I tried deleting the items, I tried returning the items.

I've deactivated the option to cloud sync before and after deleting, restarted at any possible point during that sequence, deleted all sync related files in the Documents folder under Manifest, CloudSync and Annotations, all to no avail. Every time ADE loads up, it syncs the whole steaming pile of dead files right back into my library.

This of course is on top of the fact that with large format pdf-files ADE is practically unusable anyway, scrolling is a nightmare and zooming unavailable. For no technical reason whatsoever, of course, as the very same files are perfectly readable in Acrobat, once a magical fairy has kindly removed the DRM for me. Are you by any chance actively trying to break ADE?

Free software or not, this is a disgrace, especially given the fact that this issue has cropped up for over half a decade now, judging by Google searches. Libraries and publishers should abandon this deeply flawed system.

I had the same problem with expired books, but when I then downloaded another book from the library I checked and it had added an entry into cludsync.  I then deleted the new "active" book entry and the old expired one at the same time and that worked!

I posted a fix that worked for me at forums.adobe.com at epub books will not remove from my library