I have seen two types. One has a screw you take out then pull the lock.
The other has a thin spot in the casting near the inner end of the lock assy below the turn signal switch.
You pierce the thin pot metal in the proper spot and press a spring loaded tang on the lock assy to remove it. I don't remember if this lock also has the screw or not.
If you look at a replacement lock, you will see how it works.