Gmail? Well, that will delete your whole Google account and if you have a YouTube account on it, you could lose that I guess. Click on your name in the top right corner. A box appears. Click on "Account" in blue. Once you're on the "Account" page, scroll down. Under "services", click the second link, thus closing your entire account and deleting all services and info associated with it. If you don't want that, look at the other two links under "Services" and they might help you.