Is there a way to select/ delete all of the conversations in my archived / sent / inbox at one time, rather than needing to "click" every message and then delete?

In other-words, emails and such have an option to click the first message, hold shift, and then click the last message; all messages are then highlighted / selected, thus allowing me to click "delete" and all messages are gone in one click.  OR is there a delete all option, like when you empty an email folder / trashcan?