How do I change the disk on this thing?

Bosch is pretty good brand...
I have a Makita at work.
Anyways.....
Left thumb on button and right hand channel locks.
Turn round retainer nut.
Makita round retainer nut has a key way that can strip and make it hard to get the round nut off.
The nut acts like a clutch.
30 years ago when I was welding, I loosened grinding wheels with a chipping hammer.