Here's a javascript example that I found:
Code:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Deselect A Radio Button</title>
<script language="JavaScript" type="text/JavaScript">
<!--
function uncheckRadio() {
var choice = document.form1.RadioGroup1;
for (i = 0; i < choice.length; i++) {
if ( choice[i].checked = true )
choice[i].checked = false;
}
}
//-->
</script>
</head>
<body>
<form name="form1" method="post" action="">
<p>
<label>
<input type="radio" name="RadioGroup1
" value="1" ondblclick="uncheckRadio();">
Apple</label>
<br>
<label>
<input type="radio" name="RadioGroup1"
value="2" ondblclick="uncheckRadio();">
Orange</label>
<br>
<label>
<input type="radio" name="RadioGroup1"
value="3" ondblclick="uncheckRadio();">
Grape</label>
</p>
</form>
</body>
</html>