ICloud
Internal
Overview
iCloud is a syncing system, where the data is centrally stored in the cloud, accessed by multiple devices and locally cached by those devices. iCloud drive is setup so that anything stored locally syncs to the cloud and anything in the cloud syncs locally. Deleting from one location would delete from another.
Configuration
System Preferences → Internet Accounts → <User>'s iCloud
iCloud Drive
iCloud Drive Configuration
System Preferences → Internet Accounts → <User>'s iCloud → iCloud Drive → Options
Storage Capacity
Storage capacity used so far: https://support.apple.com/en-us/HT204247
Apple Menu -> System Preferences -> iCloud -> colored bar at the bottom of the window -> Manage.
Access it from command line:
/Users/ovidiu/Library/Mobile Documents/com~apple~CloudDocs
Local iCloud Drive File Storage
iCloud Drive has hidden shadow copies of the files in the local user library in ~/Library/Mobile Documents
iCloud Drive Cleanup
Go to iCloud account: System Preferences → Internet Accounts → <user>'s iCloud.
Unselect iCloud Drive.
Note that when unselecting iCloud Drive, all documents stored in iCloud will be removed from this Mac. The documents will remain available in iCloud Drive. Select "Remove from Mac". The effect is removing the content of /Users/<username>/Library/Mobile Documents.
⚠️ However, it will make a backup in the user's home directory in "iCloud Drive (Archive)" so if you don't want to keep that on the machine, remove it.
Log out from the → Remove the account with the "-" option.
iCloud Contacts
iCloud Contacts Local Storage
~/Library/Application Support/AddressBook
iCloud Contacts Cleanup
Go to iCloud account: System Preferences → Internet Accounts → <user>'s iCloud.
Unselect iCloud Contacts.
Log out from the → Remove the account with the "-" option.
For safety, remove ~/Library/Application Support/AddressBook, but this might render Contacts unusable, so this is appropriate only when surrendering the machine.
iCloud Calendars
iCloud Calendars Local Storage
~/Library/Calendars
iCloud Calendars Cleanup
Go to iCloud account: System Preferences → Internet Accounts → <user>'s iCloud.
Unselect iCloud Calendar.
Log out from the → Remove the account with the "-" option.
For safety, remove ~/Library/Calendars, but this might render Calendars unusable, so this is appropriate only when surrendering the machine.