Is it a decal? My first thought would be Naptha. Whatever you use, make sure to pick out a spot on the screen that you don't mind gets a little effed up, and dab a small amount of solvent on there, make sure it doesn't do anything funky to the lexan. You don't want to cloud the windscreen, I assume.
A hair dryer plus fingernail might work well also, just be sure not to get the screen too hot.
To get mine off, i sprayed some adhesive remover specially made to use on polycarbonate and other plastics. Then i used my fingernail to carefully scrape away the edges. Little by little the sticker started to come off, but it was a pain and took a lot of repeat steps. Spray, scrape with fingernail, spray, wipe, repeat. Pain in the rear!
I used the corner of a old gift card instead of my finger nail to get my tank sticker off. Worked great. Not a scratch. Just takes time and patience.
Don't know how the plastics would fare with this technique.
