How to clean Kobe Vii?

Yes I know, Im a little late for this post. But I asking if anyone has a solution to restoring the whiteness of my kobe vii's back to its color. When I first bought them, they used to be white, not that I've worn them alot, its kind of yellow. Any Help? Please?

LEFT: Kobe Vii Concord RIGHT: New Kobe Vii Lakers Home.