Cannot Delete a Folder in Outlook IMAP Acct.

I dragged a bunch of folders that I'd created in my POP account ("On My Computer") into my IMAP account. They all copied successfully except for one folder. It is "stuck." It's in the list of IMAP folders but it is not synched, and it cannot be deleted. (For what it's worth, its name is in black type, while the other folders' names are in gray.) I have tried dragging it to the trashcan, Control-clicking it ("Delete" option is grayed out), updating my Outlook (I now have 14.5.2), restarting my computer...Nothing. How can I kill off this folder? It's empty and worthless to me. Thanks everyone.