The paint isn't going to hurt your tree. What's going to hurt--and maybe kill--your tree is the fact that you're compacting the root area with debris and probably traffic. You didn't fence off the root area and built inside it's dripline. The tree needs the roots undisturbed to the dripline of the tree, and should have been protected from your workers from the beginning with fencing, barbed wire if necessary. A little Goof Off will take off any paint, but if you really want to save this tree, you'd best engage the services of a certified arborist pronto. NOT a tree hacker, an arborist.

Leave the paint alone.
It will be gone in a year or so, and trying to remove it risks doing more damage to the tree.
As noted above, the area under the drip line (and a few feet larger) should have been marked off and protected.

How far is the tree from your house? I'm needing to dig a basement wall about 18lf from a 28"diameter oak myself. I don't know if its inside the dripline or not, the tree is tall and upright with few remaining branches. Problem is its on my neighbors property by a few feet or else i would just cut it down. I know I don't have the right to cut down the tree but do I have the right to cut into the root system since it is in my property ?

I guess I will go ahead and rope it off. not much is happening under the tree though. Are you saying people cannot walk under the tree or drive over it?

I've seen all kinds of things including driveways ran over the drip zone of live oaks and never seen an issue so I'm not certain why both replies suggest I'm ruining this tree. If this is the case then my entrance to the property would have dead oaks on both sides of it from 25 years of driving in and out of the property with heavy trucks and tractors and such and this is not the case, those oaks are alive and doing well, so i'm really confused.

When my wife and i were marking trees to go when clearing our property, we spotted w/ paint at eye level the trees that would be gone. We only cut down trees that were necessary. We ended up placing the house 5' over to one side for septic reasons meaning that a few of the marked trees could stay. The paint is barely noticeable now after 4 years. It will go away.

the paint won't be that deep, it will wear off in a year or so. if you want it quicker than that, use a wire brush to LIGHTLY wipe it off. the bark will recover shortly as long as you don't grind down to teh meat.

as far as protecting the roots, you should have them move the stuff from under the tree and rope it off to prevent possible damage. i doubt it is hurt yet, those oaks have a strong root system. the one at my dad's house was used for shade tree mechanicing(wear do you think that expression comes from) for many years. it had everything from light cars/trucks to bulldozers parked under it, sometimes several at once. never hurt it. once an oak gets it's roots established and reaches maturity, you won't kill them by just placing stuff on and driving over the roots unless you are cutting a bunch of the roots.