While it's never easy to remove permanent marker, there are some things you can try. This is a guide about removing permanent marker from plastic.
How can you remove Sharpie permanent markers stains from plastic headlamp lenses?
By Jeremy from Richmond, VA
ordinary every day nail polish remover will take it right off. Just put some on a tissue or cotton ball and saturate the cloth. Make sure you rinse that headlight off after removing the magic marker, I dont know if nail polish remover causes damage to a plastic headlight after long term exposure.
I wouldn't use nail polish remover on plastic.I'd try something like WD40.
I would try rubbing alchohol first. Do a "test" on a corner to make sure it won't cloud the plastic, but I think it will not.
Try Oops or GooGone.
How to remove sharpie marker off the back of a TV?
Sakeitha from TX
There is a product at the supermarket called "Magic Eraser" from Mr. Clean. It takes off anything, including Sharpie Marker marks. My son decided to write on several walls with a green sharpie and it all came off with the eraser. Actually I used the store brand which is considereably cheaper. It worked great! Good Luck.
Try rubbing alcohol. I've used it to take Sharpie ink off of plastic and glass.
Try aerosol hairspray. Our local "dented and dinged" grocery store marks their prices with sharpies and they have a sign at the registers to use hairspray if you want to remove the price. Worth a try.