Blot fresh nail polish from the couch fabric using white paper towels. Disregard this step if the nail polish has already dried.
Moisten the black stain with acetone. Apply just a couple drops of acetone to the nail polish residue.
Blot the couch fabric with fresh paper towels, extracting the nail polish and acetone from the upholstery.
Continue applying acetone to the stain and blotting the fabric until the black nail polish is completely removed.
Moisten a fresh paper towel with dry-cleaning solvent. Blot the couch fabric to lift any black pigment residue.