To remove stains from leggings without damaging the fabric, add more detergent directly to the stain and rub it with your fingers or a soft brush. Leave the detergent on for a while before soaking the item to pre-treat the area and make it easier to remove the stain. Apply ammonia to fresh stains or white vinegar to old stains, rinse, and launder using the hottest water safe for the fabric or wash with an enzyme product or color-safe bleach. Hydrogen peroxide is an effective natural stain remover, especially on blood and rust.