If you don't wanna risk an exacto knife, just put a screwdriver in the hole at the base of the torso and use it to gently pry it open. That's usually how I do it unless I think it's glued (as in the case of the BJ's 8 pack Storm Shadow and any of the Ninja Force Figures), then I pry with the screw driver and slide an exacto knife to work the seam slowly.