[Kube]

You do not need to remove the lock to remove a handle. You do need to remove the screw (it's in the door jamb) though. Then, simply pull it out.
The lock cylinders can be a test in patience if the set screw is rusted in. the screw is a #8 if I recall correctly. Being that small and threaded deeply in to a sheet metal "sheath", well, if it is rusted, think "lots of patience". I typically will remove the door panel and heat the threaded "sheath" and slowly twist the set screw back and forth to remove it.
Authentic set screws had a slotted head which makes this task even more of a challenge.