​x
 
<html>
<head>
<script type="text/javascript" src="/jquery/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
  $(".btn1").click(function(){
    $(":selected").hide();
  });
});
</script>
</head>
<body>
​
<select multiple="multiple">
  <option>Volvo</option>
  <option selected="selected">Saab</option>
  <option>Mercedes</option>
  <option>Audi</option>
</select>
<br />
<button class="btn1">Hide Selected</button>
</body>
</html>
​