Warning: Apple doesn't allow turning off 2-factor authentication anymore. You need to enter a 2-factor authentication code every time you want to view the iCloud backup data.

Apple removed the option to turn off two-factor authentication on some Apple IDs created in iOS 10.3 or macOS 10.12.4 and later.

• If you recently enabled two-factor authentication, however, you can unenroll for a period of two weeks. Just open your enrollment confirmation email and click the link to return to your previous security settings. 
  

• Contact Apple support and ask them to disable two-factor authentication for you.