How to delete all emails on your gmail account?

I have over 15, 000 emails on my gmail inbox and I'm not going to go through and delete them individually and I can't figure out how to delete them all at once? How do you do this on a computer or on an iPhone?

In Gmail, you should see a check box in the menu bar right above the messages where you can Select All, None, Read, etc. Click on the box to Select All. This will only select the messages in that view. A message should pop up at the top of your emails asking if you want to select all messages in Inbox. Click that. Then click Delete. And all messages should be deleted.

In gmail no option is here to delete all emails at the once time. Click email one by one and delete it.

When you click on "select all" email then in the middle "select all the conversations inbox" option is displayed, if you click on it then you will be delete your all emails in your inbox.