Hi,
I have taken an assumption here that your iFrame displays a webpage which belongs to the same domain because cross-site scripting is not allowed.
I have 2 pages. 1) index.html 2)iframe.html
-------------index.html-----------------
<html>
<head>
</head>
<body>
<iframe src="iframe.html" id="iframe1" />
</body>
</html>
------------iframe.html-------------------
<html>
<head>
<script type="text/javascript">
function hide(){
var parentWindow = window.top;
parentWindow.document.getElementById('iframe1').style.display='none';
}
</script>
</head>
<body>
<input type="button" onclick="hide();" value="Close">
</input></body>
</html>
Thanks
Srikant