Delete contacts in Contacts on Mac
You can delete one or more individual contacts at any time.
In the Contacts app on your Mac, select one or more contacts.
Press the Delete key.
If you select contacts who belong to a group, click Delete in the message that appears.
You can’t delete contacts in read-only accounts such as Google and Yahoo; you must delete the contacts directly in Google or Yahoo, for example.
If you don’t want to see contacts from a specific account, stop using the account in Contacts. To do so, choose Contacts > Accounts, select the account, then deselect its Contacts tickbox. If you want to see the contacts again, select the tickbox again.