Choose Between Delete and Archive

If you are more in favor of deleting emails that you have read and not archiving them, you can change the default setting of the Mail app such that it gives you the Delete option on swipe and not Archive.

How? On your iOS device, open Settings, tap Mail, Contacts, Calendars and then tap the email account that you wish to change. There you’ll see an option that says Archive Messages. Turn it off and now you can send your messages from the Inbox straight to the Trash folder.