This chinese elm came with a surface root cut off. I'm planning on how I will shape and train my tree in the future but I could really use some advice on dealing with this root.

No picture.

Hard one. UImus builds thick unbalanced surface roots like that if left for its own. Rebuilding a new nebari is possible. But I dont think it can be as good as if worked on correctly from the beginning.

I would gently lift it from its pot, and plant in a bigger pot to the point that the trunk of the tree is burried a few cm. In spring revisit. You can then probably trim back the roots substrantially. If not you can still groundlayer the base of the trunk