I have scar on my face due to stitches. so how can remove this scar.?

Many options: There are many different ways to try to improve the appearance of scars. The best place to start is with a consultation with a dermatologist or plastic surgeon who can review the expected results with skin care, resurfacing procedures, injections or surgical techniques. Unfortunately this is often a difficult problem and you need to go in with the expectation of improvement, not perfection.

Improve, not remove!: Stitches did not cause the scar, the initial injury did. Badly placed, too-tightly tied, or left-in-too-long stitches can add to the scarring. Scars are permanent, but plastic surgeons can do many things to help them be less visible as they heal and mature, including re-excising them and starting over with better technique, materials, and duration. Many otc remedies can help but not remove!

Varies: If the scar is new, massaging the scar with preparations aimed at improving the appearance of scars can be quite beneficial. Keep the area from tanning to reduce the chance of pigmentation. If the scar is mature, laser treatment or revision may be needed.