How to remove black scars on legs?

As you mentioned you have acne scars on your legs. Acne usually doesn’t come on legs. Need to consult a dermatologist to diagnose your problem. Folliculitis on legs is a very common skin condition. This happens usually due to repeated waxing on legs. This waxing gives rise to the ingrown hair on legs. This ingrowth gets infected & form folliculitis. This folliculitis may look like acne. This infection gradually turns into a Post inflammatory hyperpigmentation(PIH) on the affected area. This PIH usually takes a lot of time to reduce as repeated trauma occurs due to waxing.

A permanent hair reduction with the help of laser is a treatment of choice. In this procedure, a thick, coarse hair on legs gets permanently destroyed due to laser energy & loses its capacity to regrow. This results in a gradual permanent reduction of hair growth on legs. After multiple sessions of laser hair removal, one can expect a significant reduction in hair growth. However, Still, if any spots of PIH remains on the legs, it can be treated with various topical medications, chemical peels, Fractional Q switched 1064 Nd Yag laser. Chemical peel treatment helps In exfoliation of upper dead layers of skin & helps to lighten the superficial level of pigmentation. Laser treatments help to target melanin pigment in the dermal level of the skin. This helps in gradual reduction in skin pigmentation & skin lightening.

About your 2nd problem, dark knees are a more common condition because of friction, rubbing on the area, a thickness of skin is more at the joints. Pigmentation of the knees can be reduced by means of chemical exfoliation with chemical peels, skin lightening creams, laser treatments. The darkness on the knees can be reduced, but difficult to get rid of it completely.

We request you to consult a board-certified dermatologist, who can diagnose your skin condition & can guide you best as per your expectation & skin requirement.