Use the instructions below to remove an Exchange account on your iPhone, iPod Touch, or iPad. These steps apply to devices running iOS 5.5 or above.
Go to Settings > Mail, Contacts, Calendars. The Accounts screen will open.
On the Accounts screen, tap the Exchange Account you want to remove.
Scroll down and click Delete Account. A Delete Account warning window will open.
On the Delete Account warning window, click Delete Account to finish. You have successfully deleted your Exchange account.