Great question. Currently we do not automatically delete the users physical record from database unless the directory sync is being used. In which case , we will disable the user and their group membership.
Note* Before physically deleting a user, be sure all objects owned by that user is transferred to new user
The users group membership will only be revoked, not deleted so the objects will remain. You will still have to manually delete the user. Before deleting a user, a Incorta will ask if you want to transfer all owned objects to another user. If we were to automatically delete users, the objects assigned to the deleted user would be affected as well.