Clean the painted plastic with a sponge and soapy water to remove any dirt, oil or residue before applying the lacquer thinner.
Saturate a soft cloth with lacquer thinner and wipe it over the painted area. Allow the thinner to soak into the paint for 20 minutes.
Scrub away the paint using a scouring pad and a firm, circular motion. If the underlying plastic is very sensitive, use a bristled scrub brush instead.
Wipe away the residue with a wet cloth.
Repeat Steps 2 through 4 for any other painted areas of the plastic.