How to pass the reference of an object?

I'm trying to pass the reference of an object that is in a list to another list, without having to delete the object and updating the first list so that the object is no longer referenced in it.

The code is inside a thread , but when I try to pass the reference of the object and deleting from the list some error occurs and the list does not update the objects correctly.

Follow the code:

tthread.Queue(nil,
  procedure
  begin
      if (ListaSala.Count < LimiteSala) and (ListaPessoas.Count > 0) then
      begin
        ListaSala.Add(ListaPessoas.Extract);
        ListaPessoas.Items[ListaPessoas.Count-1] := nil;
        ListaPessoas.Delete(ListaPessoas.Count-1);
        if ListaSala.Count > 0 then
          Memo1.Lines.Add(ListaSala.Items[ListaSala.Count-1].NomeToString() + ' entrou na sala');
     end;
     Label5.Text := ListaSala.Count.ToString;
  end);
sleep(2*Segundo);

Any light?