While you are looking at the list of emails in your inbox, look at the top right. You will see Edit. Click on it. Now your emails have empty circles at the left of each one. Just touch each circle to ‘mark’ it. A check will appear in the circle. Now look to the very bottom. You will see Mark, Move and Trash. Just touch ‘Trash’
And, by the way, do not post the same question more than once. It does not get you an answer any quicker.