Rinse the bleached area immediately with cold water
Blot the spot with a clean white cloth
Mix a small amount of mild detergent with water
Gently wash the stained area by hand
Rinse thoroughly with cold water
Repeat if needed
Use rubbing alcohol on a cotton ball for small spots
Apply fabric dye or marker to match the color if the bleach mark remains
Take the garment to a professional cleaner if the fabric is delicate
Wash the entire garment after treating the spot