Again, the AK normally has a spring-loaded pin that locks muzzle attachments in place, and the muzzle is LEFT HAND threaded, You unscrew the opposite way as normal right hand threads.
If you see NO spring-loaded pin on the sight base, the brake is welded or brazed on.
If you can't unscrew the brake, it's almost certainly either welded or silver brazed in place.
If it's factory, it's welded.
Look around the brake and you'll most likely see a small bead of weld holding it in place.
You'll have to use a jeweler's wire saw or a small Dremel cut-off wheel to cut the weld.
If you see no weld, and the rifle was bought used, it's probable someone silver brazed the brake on.
You have to heat the muzzle to a red heat of around 1100 to 1200 degrees to melt the braze as you unscrew it.
Most likely case is: The brake is welded in place, or you're still trying to turn it the wrong way.
When looking down the barrel from the muzzle, unscrew the brake by pushing in the detent pin and turning the brake CLOCKWISE.
Again, if there IS no locking pin, the brake is almost certainly welded or brazed, and no amount of wrench work will turn it.