Messages in Trash cannot be deleted

I have  4 messages in Trash that  I cannot delete. 

I have tried delete, empty trash, move and nothing gets rid of them.

I repaired the folder and that did not work.

I backed up and restored and that did not clear them.

New messages appearing in trash can be cleared OK

I notice the conversations.dat in one of the folders on disk  contains the text of the email 

The Imap folder does NOT contain the message on the iMAP server, I have checked with other email clients

What shall I do?