OK, another update.

1. The folders are not subscribed folders so I cannot unsubscribe them.

2. It is not due to any of the secondary .pst files.

3. It is not due to Add-Ins. I disabled all Add-ins and the problem continued.

4. I used the MFCMAPI tool to delete the folders and they returned.

I believe these folders reside on the IMAP server. I will call my ISP and see if they can delete them from my account.