[Users] Unable to delete IMAP sub-folders

[edwardp at linuxmail.org]

ISP is Comcast (U.S.). For one of my e-mail accounts, two sub-folders
unexpectedly appeared under the Trash folder, Archives/2016. I do not
know where these came from, they are not listed for folders when using
their web interface and when I try to delete them in Claws, a pop-up
appears that they cannot be deleted.

In Thunderbird, they can be deleted, but when it is launched again, the
folders re-appear.

Is there any possible way of deleting them? I tried deleting the
account then recreating it, but that had no effect.

Thanks in advance.