How do you delete the contacts from "All on My Mac"

If you delete them from your Mac, then it will probably delete them from iCloud. Open up the system preferences, and click on iCloud. Sign out and select not to store contacts on your computer. This should delete them. Confirm by opening address book. Then, sign back into iCloud and the address book contacts should reappear.

Just to be on the safe side, I would export my Mac AddressBook prior to any of the suggested changes. 🙂

Address Book / File / Export / Address book archive

Signing out will not delete them from iCloud. Do it and read the message. It will give you the option to store address book contacts locally or just in iCloud. It will tell you that they will be available in iCloud when you sign back in.

In Addition, signing your mac out of iCloud does not sign your other devices out of iCloud. Any info in iCloud will still be available to other devices.

You can also access iCloud from the website https://www.icloud.com , which you can access from any computer at any time.

It won't delete them from iCloud. If you're afraid, try one and see. Then proceed to delete them all. Just make sure you're deleting from the On My Mac section and not the iCloud section.

Note that when you delete the last group from On My Mac, On My Mac will disappear. To make it useable again, go into Address Book's General Preferences and set On My Mac as the Default Account. Add a group or contact to On My Mac and you can switch the Default Account back to iCloud.