Ability to remove local users even when linked to labels comments or favourites

Had to delete users after moving to LDAP based users. Manual list a bunch of restrictions, the most critical seems to be:

1. You cannot delete a user who has created labels or comments about build results.

So how do you delete a user that has build results? We ended up deleting all of our build plans. At first we thought that we could just delete our build results, but the link to do that lead to deleting plans. How do you delete build results?