The best way to remove acrylic paint is to first scrape off as much of the paint as possible with a blunt tool such as a plastic spoon or a credit card. Once you have scraped away as much of the paint as possible, you can use a paint remover or a solvent such as rubbing alcohol, acetone, or lacquer thinner to remove the remaining paint.  Make sure to wear gloves when using any of these solvents and test a small area first to ensure that the solvent won't damage the material underneath. After the paint has been removed, use warm soapy water and a cloth to wipe away any remaining residue.