Can't delete duplicate Spam folder

I am new to Thunderbird, and attempting to use it as my email client. So far I have imported my main Gmail account, a second Gmail account, as well as three different Microsoft accounts. There is a duplicate Spam folder on one of the Exchange accounts, which I assume came with the import. There is, however, no way to delete the Spam folder from the original MS account. None of the other accounts has this issue, although when I had duplicate Trash folders on Gmail accounts earlier, I was able to delete them from the original account, which allowed them to disappear from TB. The Spam messages in TB actually only populate into one of the Spam folders. Any ideas what else I can do to get rid of this superfluous Spam folder, please? Many thx for any help!