谁能帮我的漂浮广告加个关闭按钮

全部代码在此，小弟水平有限，请各位大大帮我加个关闭按钮
<html>
<head>
<title>始终漂浮在左下角的菜单</title>
<meta charset="gbk" />
<style type="text/css"> 
*{padding:0;margin:0;}
html{height:100%;}
body{height:200%;}
.box{position:absolute;width:100px;height:100px;background:#ccc}
</style>
</head>
<body>
<div class="box" id="box1" style="bottom:0;left:0;">
  <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,19,0" width="300" height="250">
        <param name="movie" value="http://www.rdzx.com/pic/jsyh300250.swf">
        <param name="quality" value="high">
        <embed src="http://www.rdzx.com/pic/jsyh300250.swf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="300" height="250"></embed>
      </object>
</div>
</body>
<script type="text/javascript"> 
var $id=function(id){
return (document.getElementById(id)) || id;
}
var locked=false;
var scroll=function (o){
var space=$id(o).offsetTop;
$id(o).style.top=space+'px'; 
var fixed = function(){
if(locked) return;
locked=true;
var roll=setInterval(function(){
var height =document.documentElement.scrollTop+document.body.scrollTop+space;
var top = parseInt($id(o).style.top);
if(height!= top){
goTo = height-parseInt((height - top)*0.9); $id(o).style.top=goTo+'px';
}
else{
if(roll) clearInterval(roll);
locked=false;
}
},50);
}
return fixed;
}
window.onscroll=scroll('box1');
</script>
</html>