Done quite a few of these. Cut the stump end and pull it away from the standing tree. Might be able to save the other tree this way. Severing the football is tricky. My method is cut through about two thirds of the stem from the side, leaving a substantial "trigger" on the other side, then cut the trigger with a cheap polesaw. Depending on the forces, angled cut to get the stem to drop when the rootball settles back. Then pull the tree back out of the bind with a really strong hand winch of some sort. Usually require a second butt-cut horizontal with the ground, and angled up slightly so it will skid and not dig in, as you pull it. Wedges, lots of wedges.
