You can choose to return to the Inbox after viewing and you delete/remove an email using a setting. Open the app settings (View) and open the the "Email" section. Change the setting "Go back after removing an email that is being viewed" to your preference.
Note: This always applies to an iPhone but only applies to an iPad when you have the "Full screen view" enabled in the action menu (circle with 3 dots button) in the top of the screen.