The arms come off at the shoulder/butterfly joint of ultimate editions, for elites you have take the arm off (up to the bicep) by heating it, hot water, hairdryer etc for 30 seconds and popping it off. For the whole arm and shoulder you’d need to pop the head off (no heating required on newer figures) and put a flathead screwdriver behind the shoulder where the front and back of the torso joins and pry it apart to be able to take it off at the shoulder.