I just use a hack saw, and saw across the coil on the opposite side as the tab. I place the assembly in a vice and gently tighten. The laminations can be easily distorted, so don’t go crazy. The hack saw should be cut down to the laminations, without cutting into them. It works easily and does not harm the laminations like attempting to force them off. Then use a screwdriver to pry the coil open.
Steve