How can I turn off 'Find My iPhone' after selling the phone?
You can remotely remove the phone from your account using the iCloud website. Apple has a page with instructions on how to remove your device from Find My iPhone.
Log into the Find My iPhone part of the iCloud website.
Select your device from the drop-down list at the top of the screen.
Click on "Remove from Account".
This should remove your account from the device and enable the new owner to use it.
