Haha ... this has got to be the worst job on earth! And a chainsaw is no good for it. As much as it seems like adding work, I'd suggest backing away from the trunk a bit (as the density lessens exponentially with distance) and trying to attack roots, one by one, getting under them and removing a section (8" to 10") of each. It is a slow process, but eventually, it picks up steam and there will come some headway. I know many people use the sawsall, but I find it easier and faster to use the 10" folding pruning saw. Try to carve out a little soil from below each root before you cut out a section. The goal is not just to cut the roots, but to carve out space, because eventually, you'll need to be able to get to roots at the bottom of the stump. Once you can create some cavity around the whole stump, you may be able to start rocking it and break some roots that are hard to get to.

Forgot to add pic ...

Here is what it looks under the root. The blue line represents the boulder. This is why I was thinking to break through at the root. I have been digging all around and think the tree grew over a boulder making it more difficult. The roots above I was able to cut through but I'm sure I'm still missing roots. You think sawzall isn't as good compared to printer? I also use the axe to help.

"You think sawzall isn't as good compared to printer?" That must be some kind of typo...? I suggested the 10" folding pruning saw .... which is better than sawzall. It cuts quicker and gets into any space. (And yes, I'm comparing to Sawzall pruning blade.) I'd keep working my way around the circle and eventually, it will give.

I'm not sure if you're saying there WAS a boulder where the blue line was. I don't see one now.

Uprooting the roots of a tree with a chainsaw is a very strange idea. There are much simpler and faster ways. If you use a saw, you can damage it that way. To be honest, the best solution (and also the fastest) to your problem is if you call people who specialize in this. Their services do not cost a lot of money, so there will be no problems with this. If you do decide to use a chainsaw, then I strongly recommend that you use chainsaw chaps so that your legs are protected, since the chainsaw will be just at the level of the second legs. If you do not know which ones are better to choose, then I advise you to read this article https://afterpaints.com/best-chainsaw-chaps-review/. Good luck!

Think of it as free therapy - and who among us couldn't use that these days! Use Yard's method, and go at it as your temper or anxiety rises. There is nothing more satisfying than getting out a big root. Same for the rocks. They're always bigger than you thought. I would add the tool of a nice long crowbar and a small mattock to get at small rocks and chunks of dirt. Pile up the pieces to remind you what you've accomplished. you have me wanting to go out and attack one of mine...

If you try to chainsaw it out, you will end up dulling your chainsaw blade like crazy as hit hits the dirt. You're going to have to dig it out or have a professional stump grinder deal with it.

A chainsaw is the best stump grinder, but really better not to contact dirt, because it can dull or even broke the blade. I had the same problem with the old tree stump in our yard and I used my DEWALT chainsaw https://www.auditpowertools.com/ to cutting it. More than that, I used a crowbar to uproot the stump, because its roots and bark went deep into the ground. So, I'm sure that with the help of a good chainsaw and some kind of metal stick you will uproot the stump easily. But be careful and don't hurt yourself.