To delete all emails on Gmail, navigate to the inbox that has the emails you want to delete and select all of the messages on the screen. Click the trash icon to move all the selected emails to the trash.Continue Reading
Select the inbox tab to show the group of messages you want to delete.
Select the messages that are currently visible on the page by using the checkbox in the toolbar above your messages.
Click the “Select all conversations” link to select the rest of the messages if you’d like to delete at once, rather than deleting them one page at a time.
Click the trash icon button located in the toolbar to delete all of the selected messages.