To deactivate iCloud, iOS users can go to Settings, tap on iCloud, scroll to the very bottom, and tap Sign Out. In iOS 7 or earlier, instead of Sign Out, it says Delete Account. In OS X, users can sign out of iCloud through System Preferences.
Instead of turning off iCloud completely, users have the option to turn off certain iCloud features on the iCloud page in Settings on iOS and System Preferences on OS X. Users can deselect Mail, Photos, Contacts and other features, stopping iCloud from saving backups of the deselected features and personal information onto Apple's iCloud servers.