Is it possible for the trapezius muscle to be surgically ablated?

The technique that is used is electrocautery release of a portion of the attached muscle fibers. Through a small incision located near the muscle attachments some of the muscle fibers are released from their origin. This will cause eventual atrophy of patriot of the muscle while still maintaining its function. It is the technique that is used in the calfs and can be applied to any muscle including the trapezius muscle.

Thank you for your question. The short answer to your question is Yes.I frequently reduce the calves using minimally invasive techniques to reduce the bulk of the calf muscles that make it prominent and unattractive to many of my patients. It is highly effective.I have also used the same technique to reduce bulky large trapezius muscles to reduce their size. Although this is an unusual and not very common procedure, some patients have need of this to reduce an unattractive jump that is mostly muscle and not much fat in that area to liposuction out.

This procedure is very rare and aggressive.  Typically, extra bulk in the calf is from fat tissue and not muscle.  Not always but most of the time.  I would recommend an exam by a board certified plastic surgeon to determine what is actually causing the unwanted bulk of the calf to decide what is your best option.
When discussing your situation, the muscle you are interested in is the gastrocnemius, not the trapezius.  The trapezius is a muscle in the upper back.  Good luck!