Just let him leave on his own time, then remove it. So long as your ambients are correct he'll be okay not always on his hot spot. Maybe downsize his other two hides so when he does leave he's not as tempted to go back? You'll do more harm than good trying to get him out of there when he's crammed in and doesn't want to go. If he's a baby he'll get hungry soon enough and leave to look for food.