Try:
1.rubbing them with a tissue soaked with rubber alcohol
or
2.use break fluid.Soak them for a day and then rub them with a tooth brush.
I haven't tried the second,but some friends of mine said they successfully removed paint from plastic warhammer figures without damaging the plastic.
Far over the Misty Mountains cold, To dungeons deep and caverns old. The pines were roaring on the height, The winds were moaning in the night, The fire was red, it flaming spread, The trees like torches blazed with light.