Sural nerve damage my boy has had 13 surgeries in his foot and still is hurting him, now his doctor wants to remove part of the sural nerve. Safe?

Sensory. The sural nerve provides sensation to the outside of the foot.Removing it will also cause numbness but no movement problems. If you are not comfortable about his recommendation seek for a second opinion.
Sural nerve. The sural nerve is a sensory only nerve. No motor or muscle function. We do biopsies of it and harvest it for nerve grafting all of the time. It will leave numbness in the distribution of the nerve. That may help if pain is in that distribution.