Bite by dog just above my left knee 10 yrs ago. The scar hurts if pressure is put on it. Can scar tissue be removed?

Yes, sometimes. Has this been examined? It could even be something as bizarre as a broken tooth that has grown into the wound. If not, certain laser treatments can be effective.
Maybe! Consult with a plastic surgeon to see if revising the scar is an option. You cannot remove a scar completely (just as you cannot undo an injury to the skin), but you may get one that heals better and is smaller and less painful, if possible.