The House can impeach, and the Senate can remove from office, for whatever reasons they please. The courts would refuse to second guess the Congress, since it’s clearly a “political question.”
Yes they can. They can construe overdue library books as a high crime or misdemeanor and proceed to impeachment. But, impeachment is the only way to remove a sitting President, so Adam needs to get busy convincing his fellow members of the House to bring impeachment charges. I think that Adam Schiff will be indicted first.