How do you delete all trash at once in gmail from galaxy nexus?
check all the mail and hit trash. try hitting the menu button and see if there is a "select all" option, I don't recall seeing it though. I don't much email through gmail though since I only use it for important matters.
So far I haven't discovered how to delete gmail on the Nexus in bulk. And I'd read other forums trying to do so. Checking the messages one by one is so time consuming. So instead I went to my gmail account on a computer, and made many more filters, and then archived all but the most recent by opening the filtered posts and checking the top box and then selecting All mail form the left hand column under the COMPOSE column.