Sometimes you have to delete a bunch of email in your Gmail account, but you don’t want to download it all with a mail client, and you don’t want to go through every page and delete in chunks of 50. That would take way too long.
What you do is in Gmail’s search box type “in:inbox” and press Enter.
Click the dropdown that has a little checkbox in it. Click “All”. This will select all of the email on your first page.
If you look above your email list in the center you will see a link that says “Select all 2,225 emails in inbox” (or how many emails you have).
Now click on the trash can icon.
You’ve deleted all email within your Gmail account in about 3 seconds.