How to delete all of your emails at once on a iPhone 4?

How do you delete all of your emails at once on a iPhone 4?

It isn't possible but some other ways are to
- go on your computer and do it
-or click everyone on your iPhone that's what I do. But the good part is once its in the "trash" you can delete them all at once with makes no sense. It takes me about an hour to delete 1000+ emails so now I just delete them as they come good luck!