BobLovesGrass said:
This!!!
The secret is to dig around and cut the roots with a sawzaw/Axe... once most roots are gone you can remove with a truck and rope.
I removed a big one over summer and it was a PIA multi week process.
There was a bunch of clay caked into the roots which made hacking it up very slow to burn and cut. Chainsaw blades would go dull almost instantly.
Once I got it out, I made a fire bed started it up and loaded it back in.
The clay would heat up dry out and fall off, I had to burn 3x times to get the sucker to finally go... very satisfying but took far longer then the time left you have in your seeding window.
Of course if you have some friends, you can lift the stump up into the back of a truck and take to dump, I did mine right during the virus first happening and decided this wasn't an option.
There's some videos about burning them and unless it's completely dead, don't even bother. The only reason my burn was successful was the fact that I removed from ground, let it dry out and rolled back in on top of a burning fire.
Also, took quite a bit of dirt to back fill the hole, more than I estimated.
The tree was probably 15-25 years old and not that big but 20' -25' high... depending on the size of the tree kind of determines the route.... If big I'd leave it for next season and get your overseed in.... after all the trampling, stomping, cutting down the tree itself and fire stress, the KBG has sprouted from rhizomes in the past couple months. Incredible grass it is.
If huge, I'd probably have a professional do it...
One caveat is that Pine tress have certain compounds that make them burn well, the roots will burn underground.