If Donald Trump refuses to leave White House peacefully when his time is up in the White House then Donald Trump will be arrested and forcefully removed from the White House.
Donald Trump will likely just walk out of the White House on his own when his term is up because it would be really bad looking for him to be dragged out of the White House and arrested.
Either way Donald Trump will be removed from the White House when Joe Biden Takes over either peacefully or forcefully.
The police will come in and take him out by force in handcuffs and if they have to he will be shot but that is likely not gonna happen.
Donald Trump in my opinion will likely just walk out of the White House on his own and not make a huge scene or any scene about it at all.
Either way he's gonna leave on his own accord or by force so it's best he just leave the place.