How does one delete all remote iCloud datas?

My client noticed his iPhone 6+ re-enabled its iCloud backup again even though he disabled it years ago. He turned everything off except Notes that asked to delete his iCloud Notes in his iPhones. How about only iCloud's server's and not in iPhone? Also, why does Health app use 4.5 MB when he never used it?

Anyways, he just doesn't want any of his private personal datas online like Apple's. Backups will be done locally with 2012 MacBook Pro's updated Sierra v10.12.6 (its iCloud stayed disabled)'s iTunes. 😟

Thank you in advance. 🙂