iCloud apple id change

If the iPhone or iOS device is lock to an Apple ID or iCloud account

http://support.apple.com/kb/TS4515

Or

If the email address was changed and the old one is there but it is now a new one

You might have to go to "iCloud.com"

Sign in with the new account

Select the Find My iPhone

Select the "All Devices"

Select the device

Wipe and remove it from the account

Restore the device

You can do the same from Find My iPhone App from an iOS device

if you forgot your applied password your can reset it here:

http://iforgot.apple.com/

if you switched the primary email on the account while you were already signed in then it will not find the account due to the email being different. In order to sing out you will need to do the following:

go to http://id.apple.com/

select manage your appleid

next to applied and primary email hit edit

type in your old email and hit save

sign out on your device

edit your account back to correct email