JavaScript删除HTML表格指定行的方法

Body部份：
<div>
  <table width="613" border="0" cellpadding="2" cellspacing="1" id="SignFrame">
              <tr id="trHeader">
                <td width="27" bgcolor="#96E0E2">序号</td>
                <td width="64" bgcolor="#96E0E2">用户姓名</td>
                <td width="98" bgcolor="#96E0E2">电子邮箱</td>
                <td width="92" bgcolor="#96E0E2">固定电话</td>
                <td width="86" bgcolor="#96E0E2">移动手机</td>
                <td width="153" bgcolor="#96E0E2">公司名称</td>
                <td width="57" align="center" bgcolor="#96E0E2">&nbsp;</td>
              </tr>
        </table>
   </div>
   <div>
        <input type="button" name="Submit" value="添加参与人" onclick="AddSignRow()" /> 
     <input type="button" name="Submit2" value="清空" onclick="ClearAllSign()" />
     <input name='txtTRLastIndex' type='hidden' id='txtTRLastIndex' value="1" />
   </div>
JS代码部份
<script language="javascript">// Example: obj = findObj("image1");
function findObj(theObj, theDoc){  var p, i, foundObj;    if(!theDoc) theDoc = document;  if( (p = theObj.indexOf("?")) > 0 && parent.frames.length)  {    theDoc = parent.frames[theObj.substring(p+1)].document;    theObj = theObj.substring(0,p);  }  if(!(foundObj = theDoc[theObj]) && theDoc.all) foundObj = theDoc.all[theObj];  for (i=0; !foundObj && i < theDoc.forms.length; i++)     foundObj = theDoc.forms[i][theObj];  for(i=0; !foundObj && theDoc.layers && i < theDoc.layers.length; i++)     foundObj = findObj(theObj,theDoc.layers[i].document);  if(!foundObj && document.getElementById) foundObj = document.getElementById(theObj);    return foundObj;}
//添加一个参与人填写行
function AddSignRow(){ //读取最后一行的行号，存放在txtTRLastIndex文本框中 
 var txtTRLastIndex = findObj("txtTRLastIndex",document);
 var rowID = parseInt(txtTRLastIndex.value);
 
 var signFrame = findObj("SignFrame",document);
 //添加行
 var newTR = signFrame.insertRow(signFrame.rows.length);