For those that you have already created, they cannot be deleted. Since they are living, their privacy is "Black" and no one can see them except you. One suggestion is to invite each of them to join WikiTree. Then, they can decide on their privacy level and can add a source to themselves. If that does not work, then I think you can just add something like "Personal Family Knowledge" and since no one can see them and they are living, that would be sufficient for now.