At very first, Sign out of iCloud on your iPhone, iPad, or iPod touch:
Tap Settings > iCloud on your iOS device.
- Scroll down and tap Sign Out, then tap Sign Out to confirm. If you’re using iOS 7 or earlier, tap Delete Account, then tap Delete to confirm.
- Tap Keep on My [Device] or Delete from My [Device], and enter the password for your Apple ID. Your data remains in iCloud and is updated on your device when you sign in to iCloud again.
- If you’re signed in on more than one device with this Apple ID, repeat steps 1-3 on each device.
- Go to your Apple ID account page, and sign in again.
- Change your Apple ID to the email address that you want to use. You’ll need to verify the email address.
- Tap Settings > iCloud on your iOS device, and sign in with your new Apple ID.