Flag for safety and wait for it to fall.
If you have a winch, you could pull it off the stump to get the base resting on the ground. Then I might try rolling it with a cant hook or peavey and see if it falls loose from the other tree to the ground.
If you have a tractor, I'd pull it off the stump, get a better hold on it and pull down out.
I'll add that you need to be very careful getting a chain or cable on it while still on the stump. And mindful of whether it is going to tighten or loosen as it drops from the stump to the ground. Think it through before doing.