We had an old tree removed with Roots ground down now have mushrooms

Apply a fungicide

Ok, this happens. They are not edible. Just pull out and dispose or just leave them alone and let nature do its thing.

I'd avoid fungicide as the mushrooms are harmless. They are feeding on the rotted wood below the soil level. They will eventually use it all up. You could always dig up the buried wood and eliminate the source.

As mentioned above, they are harmless. They are feeding on the rotting organic materials left behind. Keep digging and disturbing them.

I had that happen. I just kept digging out the mushrooms and eventually it stopped. I don't know about you, but mine were huge and deep. one weighed about 10 lbs. or so.