Polyethylene board cleaning

I purchased a used True Pizza Prep Table with a white polyethylene board. Any suggestions on how to clean and remove the slight staining on it? Thanks

If the stains are just on the surface an orbital sander will take them out.

every couple of weeks the girls lay bleached soked rags on them overnight cleans them right up .

Great tip…Thanks pizzabarntn!

Bleach! works no problem.

Sorry it took so long to get back, but thanks for the help.