Many topical treatments will help. Scar tissue can be melted no matter how old it is or what made it as long as it is either overgrown or still growning. If it is sunken, nothing will work.
Topical silicone sheeting helps raise the enzyme that melts scar tissue, but is a bit cumbersome. Scarguard does it also. It is a liquid that dries to an almost invisible flexible film sheet. You can never erase a scar but this product will make it look better. It is dispensed by a lot of plastic surgeons after surgeies and injuries to lessen scars.
These effective treatments SHRINK scar tissue. If you use them on this it will sink more. Be careful of NONSENSE promising to fix any kind of scar. THEY ARE SELLING YOU SNAKE OIL! No scar treatment RAISES scar tissue. This is unfortunately only fixed by possibly laser resurfacing or revision surgery. After the surgery use Scarguard to help prevent overgrowth, but non of these things now!