You can delete chat messages In Microsoft Teams after you've sent them, but you can only hide messages from other users.

Microsoft rolled out several new features for Teams in December, including the ability to delete a chat and new capabilities in whiteboard sessions that should enhance meetings. Teams users can now ...

Microsoft Teams by default will record your chat history, but this is not something that is well known. This feature is enabled in all versions of Teams, so there is no escaping it unless the feature ...