How to delete all emails in gmail?

1. In any mailbox, click on the link to select ALL messages on the page (like you’ve already intimated above).

2. At the top of the email list, gmail will inform you that “all 50 conversations on this page are selected.”

3. Immediately next to that message, you’re provided a link to select all conversations in the current mailbox. Like this.

Cheers! that did it.

I whant to delete all e-mail from my Gmail inbox

yes robmandu that works.
you can also delete from all emails from email clients like emclient and outlook easily by selecting all emails at once.

Click the button just before “Archive” and then click on the “Delete” button.

Go to your All mail view, and click “Select all” (or the drop down option All from the check box far left of Archive | Spam | Delete buttons).

Underneath the | Archive | Spam | Delete | + | – | Move to Inbox | Labels | More | buttons… You’ll see a message appear in a yellow bar that says:

All 100 conversations on this page are selected. Select all 73795 conversations in All Mail

Click on the “Select all conversations” link on the right side of the message, then click delete. This will help you to remove all the message.