Prova questo script ....
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Untitled</title>
<style type="text/css">
<!--
.normal1 {font-family:tahoma;font-size:8pt;background-color:yellow}
.normal2 {font-family:tahoma;font-size:8pt;background-color:white}
.overTR {font-family:tahoma;font-size:8pt;background-color:blue;color:white}
.clicked {font-family:tahoma;font-size:8pt;background-color:red;color:white}
-->
</style>
<script language="JavaScript" type="text/javascript">
<!--
var aTR = null;
var aTbody = null;
function selectRow(aTD) {
if (aTD.tagName == 'TD') {
aTR = aTD.parentElement;
aTbody = aTR.parentElement;
document.getElementById('canc').disabled = false;
} // if (aTD.tagName == 'TD')
} // function selectRow(aTD)
function _deleteRow(aTD) {
if (aTR != null) {
aTbody.deleteRow(aTR.rowIndex);
aTR = null;
aTbody = null;
document.getElementById('canc').disabled = true;
} else {
alert('Cliccare la riga da cancellare');
} // if (aTR != null)
} // _deleteRow(aTD)
//-->
</script>
</head>
<body>
<table summary="" cellpadding="0" onclick="selectRow(event.srcElement)">
<tr class="normal1" >
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
</tr>
<tr class="normal2" >
<td>BBBBBBBBBBBBBBBBBBBBB</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
</tr>
<tr class="normal1" >
<td>CCCCCCCCCCCCCCCCCCCCC</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
</tr>
<tr class="normal2" >
<td>DDDDDDDDDDDDDDDDDDDDD</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
<td>AAAAAAAAAAAAAAAAAAAAA</td>
</tr>
</table>
<span style="font-family:tahoma;font-size:8pt">cliccare su una riga per attivare il bottone</style>
<input type="button" value="Canc" id="canc" disabled onclick="_deleteRow()">
</body>
</html>