I deleted the child account created accidentally how come I cannot remove it from my family?

Thank you Eric! Very helpful. I contacted Apple directly. The first person I spoke to stated, "nothing could be done". I would have to wait until the 8 year old turned 13 to remove from my family even though 2 accounts were created accidentally and were requested to be deleted. I asked to be elevated to someone else, since I could not believe that such a large organization would not create workarounds for these situations and it was I, "the parent" requesting the change even with all the child guidelines. After speaking to a "senior" support tech, I was informed that as soon as the deletion of the account occurred, it would automatically be removed from my family and that I would receive an email notification of such. I was asked to give it 7 days. Today is day five, I trust that - that makes more sense, than not be able to delete at all or remove a mistake. We will see...

By child account, I meant child Apple ID.