Right now, we don't offer the option to donate your AdSense earnings directly to a charity from within your account. However, once you receive your AdSense payments you're free to use your earnings as you wish.

As a friendly reminder, if you do choose to donate your earnings, we ask that you avoid placing text on your sites saying that all or some of the ad earnings will go to charity. Because this language can draw undue attention to the ads, and since we can't verify how the earnings are ultimately used, these statements are not permitted by the AdSense Program policies.