Scrape any excess nail polish away from the leather. Use a dull butter knife, and be sure to use gentle motions.
Rub an art gum eraser across the dried nail polish stain several times. This should remove the polish. If small traces remain, use an emery board to lightly buff the polish from the leather.
Pour 1/4 cup liquid dish detergent into a small bowl.
Add 1/8 cup water into the small bowl.
Stir the mixture, using a spoon, until it forms a thick foam.
Use a clean sponge to apply the foam to the erased/buffed area.
Blot the area with the sponge to remove any eraser or emery board residue.
Wipe the area clean with a lint-free rag.