[ecfisa]

Hola Santiago14.

Para eliminar el último renglón sin perder el formato:

Código Delphi [-]
procedure TrimRE(RichEdit: TRichEdit);
var
  i: Integer;
begin
  with RichEdit do
  begin
    if Lines.Count > 0 then
    begin
      i := Lines.Count-1;
      while Lines[i] = EmptyStr do
      begin
        Lines.Delete(i);
        Dec(i);
      end;
      SelStart  := Length(Text) - Length(Trim(Lines[Lines.Count-1]));
      SelLength := Length(Text);
      SelText   := '';
    end;
  end;
end;

Saludos