Thank you for your votes and comments on this feature. The team is in the process of finalizing designs for deleting private chat threads. I will update as we have more progress to share.
An error occurred while saving the commentDM May commented
Please, delete private chats, because many times I'd never talk again with the student.
Removing the Conversation Tab is being reviewed by the feature team.
For deleting chat messages, please following progress here: https://microsoftteams.uservoice.com/forums/555103/suggestions/33535006.