Tap the “Delete,” button, seen in the lower-right corner of the screen. For confirmation that you want to delete the highlighted email, tap “Delete.”
Repeat the process for your “Spam” and “Sent” folders if you want to delete all the emails you have ever received or sent. To access these folders from your Inbox, click the 3 horizontal lines in the upper-left corner of the screen, then tap “Spam” or “Sent.” As you already know, after deleting an email, it gets sent to your Trash. Therefore, to permanently get rid of every email data you have, you need to clear your Trash as well.
From your Inbox, tap the 3 horizontal lines in the upper-left corner of the screen. In the menu that will be seen, tap “Trash.”
Click and hold any email in the Trash, then click the little circle named “All” in the upper left corner of the screen.
Tap “Delete” in the lower right corner of the screen, then click “Delete” on the pop-up menu.