The handles usually can be removed.
With my 6B SSTs, they have visible screws in the handle.
So you can take them off, but you need shorter screws then to hold the front panel parts together. I also converted a silver 17“ 6B SST w/o handles into a black 19“ unit w/ handles.
Contact Bryston with the serial of your unit and they will be able to tell you which options you have.
P.S. The 6B SST still is my favorite Bryston amp. It is an engineering marvel! I am using three of them in my home theater.