You find yourself in a position where you can effortlessly steal Hitler's wallet. This will have no effect on his rise to power, the nature of the war, holocaust etc. There is nothing important in his wallet. All that will happen is he will lose the 40 reichsmarks, and you will ruin his evening. You don't need the money, and will not be caught. Are you ethically obligated to steal his wallet? That's all the info you get. This is a question of ethics, focus on that aspect.