Deletes a contact who is not a site member or contributor.
The deleteContact() function returns a Promise
that resolves when the specified contact is deleted.
Deleting a contact permanently removes them from your Contact List.
If the contact is also a site member, the member must be deleted first, and then the contact can be deleted.
You can only call this method when authenticated as a Wix app or Wix user identity.
ID of the contact to delete.