It isn’t the function of the President to enact laws, it is his job to set policy. Laws are created and enacted by the Legislative branch, our fabulous Congress. The President can sign Executive actions/decrees which are less enforceable than an actual law, and can be undone by future Executive actions. Trump has himself reversed Obama’s Executive Orders this way.
As for undoing what he has done, I think Trump has done and continues to do more damage to the Office of the Presidency and to US standing in the world community than can easily be repaired by the next administration, or maybe the next several. Impeachment would address the immediate virus but not cure the disease.
I think it safe to say an impeachment proceeding against Trump the Tweeting Gasbag might become the ugliest political circus ever attempted.