Try cleaning it with a cleaner called Greased Lightening. You can find it at Walmart. I found that cleaner the best for any kind of surface. I used it on my yellowing lawn chair arms and it really whitened them up. Just spray it on and let it sit a little before wiping it off. The cleaner can be used on most anything. It is safe to use on clothing also for bad stains. It really works good on most anything.
There is a spray paint on the market, believe it's called Painter's Choice that is made specifically for plastics like laminate. Try this, repainting the original color or now's your chance to change the color. Yellowing is usually a result of age and probably cannot be bleached or removed withour harming the laminate. Give this paint a try.
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