Problem: When deleting a workspace via a web browser, the WWGM does recognize that the workspace has been deleted when viewing the Workspaces tab on the homepage. However when browsing to the WLD on your machine, you'll find that the WWGM does not remove the local cache of un-encrypted CAD files. This eventually leads to a terrific amount of outdated files in your local cache - in my case, hundreds of MB's within a week.
Proposed solution: WWGM obviously knows when a workspace has been deleted. That's all it needs to know to process a deletion task in the background to remove these files / folders. So in theory it's a trivial update.
Note: This is currently being tracked by an SPR as a bug, as I believe this is not just an enhancement request but the way that it should work. This is SPR 2174774.