Removing a User should use mysql statements. This is already done for the removal of the actual DB User. However, if that User is on multiple databases, this method is not used, and it would fallback to only clear the User from the mysql.db. This should not be done with the DELETE command for mysql.db, and has now been changed to use the correct REVOKE statement on each mysql.db host for that db+user, for the case: mysql_detect_correct_methods=1 which should be all modern DA boxes.