I have removed various tree stumps over the years. I strongly recommend leaving as much of the trunk as you can, so that you can use it as a lever. Ie, fasten your chain/cable high up on tree trunk. The shorter the "stump" the more powerful and more heavy-duty (and more risky) the requirements of your project will be. You can always cut the trunk off later. Also be aware the stumps like to "flop" back into their original hole without warning.