How do you make a metal surface on lammps?
You will find some metal surfaces in the examples/ folder of lammps. Your question is vague because they are many different potentials that are used for metals (EAM, MEAM, ReaxFF, etc).
I am trying to make an anatase surface, which example will help specifically
That would be your job to find out, I have no idea. Probably none of them, unless you are incredibly lucky and find a pre-digested script that does exactly what you want, but its rare.
That is not a metal.