They will beat you up using mace, batons, boots, brass knuckles and anything else at their disposal. They are the fascist anti fascists. Remember they are cowards, will gang up on you, and only attack in groups. See a lone antifa and they will run screaming.
Daniel has 60+ answers in. Politics. Not only can the new President reverse the executive orders of the previous president, but the current president can reverse his own executive orders, reinstate them, and reverse them again as often as he wants. If Obama wanted, he could reverse his new overtime standards tomorrow, and bring them back the day after.
Executive Orders are controversial because they allow the President to make major decisions, even law, without the consent of Congress. This, of course, runs against the general logic of the Constitution -- that no one should have power to act unilaterally.