Police cleared and arrested protesters occupying Hamilton Hall at Columbia University on Tuesday night at the request of university administrators, marking a dramatic climax to the antiwar protesters’ standoff. As the drama unfolded, campus officials asked police to remain on campus until at least May 17. The NYPD’s arrival on campus was its second this month, after President Minouche Shafik requested police dismantle the Gaza Solidarity Encampment the day after she appeared before Congress to discuss antisemitism on college campuses.