It’s easy and fast to delete messages in the Inbox view. Swipe the message in your Inbox across the whole screen from the right hand side of the screen to the left. This removes it from your Inbox.
To reveal other options, swipe across only half of the screen to reveal options such as Flag and More. Tapping More lets you quickly reply, forward, move to junk, and more.
If you swipe from left to right on a new email you will unveil the Mark as Read option. Keep swiping all the way across the screen without letting go to quickly mark it. If you have already viewed the email this option will change to Mark as Unread.