Leaning Apple Tree

Location: Western Colorado

We have a Granny Smith Apple growing at an angle in our backyard. We spoke with the local nursery and they had recommended digging in a large circumference around the tree and trying to straighten it and backfilling underneath with dirt. As we were clearing the rock and weed barrier around it, we noticed it has large roots growing from the opposite side of the lean, and one going in the direction of the lean. I am concerned that if we try to dig anywhere near it, we might damage it and cause more harm than good. The tree has been in the ground for about four years, it has been through heavy winds and snow and has seemed to stay solid. Is it necessary to attempt to straighten this tree at all? If so, what is the best way to do it without harming the tree?

Thank you!