Swipe left on the Home screen to access the App Library if an app isn’t there. you get to the App Library, swipe left on the Home screen. select one of your email accounts from the drop-down menu. tap Delete Account at the bottom; this may take some scrolling.
You may also use the Trash folder under Accounts and Passwords. Select Advanced Deleted Mailbox and select the Trash folder on the server to ensure it gets a checkmark – then exit out of that series of popups by pressing the relevant buttons at the top of them, then confirm whether you can delete emails.
Go to your Inbox folder. On the top right, tap on “Edit.” Pick the first email on your list. Keep hold of the “Move” button. Remove all of your fingers from the screen and wait a few seconds. Mail now asks you where you want to move all of your emails.
To choose and remove one after another, hold down the Shift key while clicking the previous email in the message list.
Open the Settings app. Scroll down and select Mail Accounts. Choose the email account you’d want to remove. Select Delete Account from the drop-down menu. Select Delete Account or, in some cases, Delete from My iPhone if you’re sure you want to delete it.