I am trying to get rid of a public folder from Exchange Online. It's existed for years (started on-prem before we migrated) and is a simple folder which mail items get moved into.
Thought it would just be a case of deleting it from the public folders, which I did. It's gone from the public folder list in Outlook and Exchange Online (checked via the GUI and using Powershell). Checked the on-prem server too for good measure (this is now just used for management) - no sign of it in any of them.
But Outlook favourites to it (desktop Outlook, subscription version), which a lot of users have, still give access to it, and it's clearly still live as if one user copies something into it, others can see that - i.e. it's not just a stale local cache. This has been the case for a number of weeks now. Doesn't seem to appear in OWA.
I have a long-running support case with Microsoft support and they are proving about as helpful as normal (i.e. not very). Latest suggestion is create a new Outlook profile. Not sure how this is supposed to help - it's clear that it still exists on the server side, so whether or not a particular client can see it isn't really relevant.