Most Helpful Girl
Scrub out with powdered cleanser that has bleach in it. Or find another cleaner in your house that has bleach in it. Do not mix bleach with other clears though. If that doesn't work, rinse all the bleach out and try baking soda and peroxide.
And do not use nail polish remover on any material that bathtubs are regularly made out of. Nail polish remover dissolves hard enamels, plastic and fiberglass.
Most Helpful Guy
Alcohol tends to be pretty good, but be careful not to damage the bathtub