If I had a penny for every time one of my horses had proud flesh I could have retired years ago. I always washed, dusted with Wonder Dust and bandaged. Once the proud flesh is gone and the wound has closed then I rubbed in the oil from a vitamin E capsule into the scar to help heal and get the hair growing back and all my neddy's only had a hair line scar afterwards to show for it.
Get the vet to cut it off. It will bleed like hell and look barbaric - but it's usually the best course of action.
To prevent proud flesh forming in the first place - Fucudin H is pretty amazing stuff (again prescribed by a vet)
How big is the wound and where is it located?
Just keep it clean and leave it it will be fine , my old TB had a horrid cut on his leg, I cleaned it and watched it, no scarring, he went to loan home ( hideous experience) but it was a horrid cut, they had it stitched , massive scar...
Not saying it was not warrented, but often keep clean and treat is all that is needed
You could leave it alone - especially if it is healing well and clean/not infected etc.
Or get a sterile stanley blade and slice it off yourself. Clean well, apply Wonder dust/Fucidin H/appropriate wound cream and away you go.
It seems to be healing okay and its not huge or really noticable. Should I put some cream on it? Ive got some wondergel for his other scars. TBH I only just noticed the scarring/wound today.