In iOS 8.3, the option to remove an email account from your iPhone is not in the native Mail app, but through the Mail, Contacts, Calendars section of your iPhone's Settings menu. The deletion process only stops your iPhone from exchanging messages with your email account; it does not affect your account's original settings and options.
Removing your account also deletes all associated account information, such as calendar and contact information
credit: Image courtesy of Apple
Step
Open the Settings screen by clicking the Settings icon on your iPhone's Home screen.
IPhone Home screen
credit: Image courtesy of Apple
Step
Scroll down the Settings screen and then select Mail, Contacts, Calendars to open the Mail, Contacts, Calendars screen.
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Both the Contacts and Calendar app settings are also available from the Mail, Contacts, Calendars screen
credit: Image courtesy of Apple
Step
Select the account you want to delete in the Accounts section of the screen.
Tap Add Account to add a new email account to your iPhone
credit: Image courtesy of Apple
Step
Tap Delete Account at the bottom of the screen.
Manage your email account's associated data from this screen
credit: Image courtesy of Apple
Step
Tap Delete From My iPhone on the pop-up box to remove the email account.
If you change your mind, you can always re-enter your email account at a later date
credit: Image courtesy of Apple
