How to remove 1000 emails at once

First tap on 'Edit' in the top right hand corner of your mail app. After you do that, you should tap the first one with two fingers and slide down. Sliding down with two fingers will continuously select the emails until you lift up your fingers. Otherwise, you can use the 'Edit' feature and then tap on each email you wish to delete. After you selected them all, bottom right hand corner has 'Trash', this will delete all selected messages.

Did all this and the emails all came back