It looks like it may be pinned...you can see a pin in the slot of the brake right beneath the rifle's sight post. Typically, the original pin is driven out and another longer pin is put in it's place to keep the brake from sliding.
This one may not pinned at all--from this pic it looks like the original pin is in place.
Once you've determined that there is no pin holding it (or you have removed the pin with a punch) you will then have to tap the brake off the barrel with a wooden dowel or brass punch. Be careful or you will mar the finish.
ive taken that pin out and its for the sights...its not conected to the break... im just starting to think i need to put some heat on it and it will slip off?
knock that pin out. knock the FH off.
method 1: Use a brass punch and you won't marr the finish but you'd have to brush off the brass.
Method 2: Use a wooden dowel and you wont even have to brush the brass off of the gun (put there by method 1).