How do I delete "Documents & Data" from iCloud?
From my understanding, once you migrate to iCloud Drive, your old 'Documents &amp; Data' storage is converted &amp; no longer exists in its old location.

Mavericks/iOS 7 can't see iCloud Drive &amp; Yosemite/iOS 8 can't see the old Documents &amp; Data, migrated or not.

Refs:  


http://support.apple.com/en-la/HT201104  
http://support.apple.com/en-la/HT201385  
http://www.cultofmac.com/296334/psa-shouldnt-upgrade-icloud-drive-ios-8-yet/  
http://www.howtogeek.com/203304/everything-you-need-to-know-about-using-icloud-drive-and-icloud-photo-library/