Change apple id on iphone 4
Is it possible to change the apple id and password for my icloud account on my iphone 4?
iPhone 4, iOS 6
You would have to go to Settings>iCloud, tap Delete Account, then sign back in with the updated credentials. This will delete the account and your synced data from your phone but not from iCloud. If you are signing back into the same iCloud account (just with a renamed ID and new password) your data will be siced back to your phone when you sign back in.
However, if you are changing to a new ID and password, you will have to create a new account and migrate your iCloud data to the new account. Delete the exising account, choose Keep on My iPhone when prompted, set up the new account with the new ID and password in Settings>iCloud, sign in, turn on your iCloud data syncing, and when prompted choose Merge to upload the adat to the new account.