[Vlasenko Fedor]

<table id="pmdform">
  <tbody>
    <tr>
      <td>1</td>
    </tr>
    <tr>
      <td>2</td>
    </tr>
    <tr>
      <td>3</td>
    </tr>
    <tr>
      <td>Последняя строка</td>
    </tr>
  </tbody>
</table>
<script type='text/javascript'>
    var el = document.querySelector('#pmdform tr:last-child');
    el.parentNode.removeChild(el);
</script>

Вариант без jQuery