What happens if you accidentally delete a teacher?

If you accidentally delete a teacher:

• The comments in assignments are not deleted.
• Messages sent to users, using 'Message', are no longer available.
• You can see in the logs that a message has been sent to the student, but not the content of the message.
• Messages sent by the deleted teacher in the course's 'News forum' remain after the teacher is deleted.

...best if you avoid doing this :)