Doesn't work unless you have an imap account. My gmail account was set up as pop years ago. I periodically delete ALL my mail at the gmail site (If the NSA wants it they can go fish!) but that doesn't affect what I've downloaded to my tablet. What I finally did was delete all the mail at the gmail site and then delete and re-install that gmail account on my tablet. What I'd like is to download all my mail to my desktop AND download it to my tablet when the tablet is on (rarely) and then be able to delete it from the tablet at will. Unfortunately, gmail won't allow you to download email more than once unless you cancel POP and then restart it, in which case you will download everything at the site that you haven't deleted. NOT WHAT I WANT TO DO. I do not want my email sitting out on the googlecloud if I can help it; I can't control how many backups they make or what they do with them, but I don't want to help them do it.
Surely it should NOT be this difficult to get rid of garbage. It's not even a straightforward "DELETE ALL" button at the website, which is what it should be. .