1. For iOS 12: Go To Settings > Passwords & Accounts For iOS 11: Go To Settings > Accounts & Passwords For iOS 10: Go to Settings > Mail > Account For iOS 9 and lower: Settings > Mail, Contact, Calendars > Add Account
2. On the Accounts screen, tap the Exchange Account that will need to be removed.
3. Scroll down to Delete Account. A Delete Account warning window will open.
4. On the Delete Account warning window, select
‘Delete from my iPhone’.
5. Once this option has been chosen, wait for the account to be removed from the device. This can take some time to remove, depending on the size of the mailbox.
6. Press and hold the power button and then select ‘Slide to power off’
7. Wait for phone to fully power off and then power back on again.