Grab a pickaxe, shovel and nice sharp axe. Dig around the base of the stump exposing roots. As you expose roots, chop a good segment of it away to slowly loosen the stump and allow you access to dig underneath it and continue searching for roots. Eventually you can use a long strong pole as leverage to pull the stump out enough to get access to the roots directly under the stump, cut them away and you're done. It's tough work but good excersize 🙂