<html>
<head>
<script>
function removeLastOption()
{
var x=document.getElementById("mySelect");
if (x.length>0)
{
x.remove(x.length-1);
}
}
</script>
</head>
<body>
<form>
<select id="mySelect">
<option>Apple</option>
<option>Pear</option>
<option>Banana</option>
<option>Orange</option>
</select>
<input type="button" onclick="removeLastOption()" value="Remove last option">
</form>
</body>
</html>