iCloud: Delete a group or a contact from a group
You can delete a group or a contact within a group at any time. You can’t delete the default All Contacts group.
Delete a group
Select the group you want to delete, then press the Delete key.
Deleting a group doesn’t delete the contacts it contains.
Delete a contact from a group
Select the group that contains the contact you want to delete.
Select the contact, then press the Delete key.
Deleting a contact from a group removes it from that group only.
If you accidentally deleted groups or contacts from groups, you can use iCloud.com to restore them from an earlier version that was automatically archived in iCloud. For instructions, see Restore your contacts, calendars and reminders, or bookmarks.