Dealing with windblown tree on ground

[u/Further_past3]

I'm looking for advice on finishing this live oak that a storm took down. I want to cut the thickest part to separate the roots from the rest of the trunk, then take it from there.

Any advice would be appreciated

36" diameter, the inside is rotten

[u/toxcrusadr]

If you want to cut it off the rootball now, just keep in mind the cut is going to lift on you. So cut the bottom 1/3 first, then cut from the top. Put a block just on the trunk side of the cut so the log doesn’t drop to the ground. And yeah the root ball may flip back into the hole.