This shows the lower end with brake-shaft, intermediate gear and main-gear.
Both the drum AND brake-shaft are held in place by the lock-plate.
Lock-Plate in down (locked) position:
In order to remove the either the drum or brake-shaft, you must pull up on it as pictured.
Lock-Plate in up (unlocked) position:
If you intend to remove the brake-shaft, use a brass drift punch against this surface only:
You will be driving out the lip seal, the bronze bushing and the brake-shaft all at one time.
IMO, there needs to be compelling reason to do this.