You can put it right after the place where you call superfish to begin
with. It's just a built-in option for superfish.
For example the top of your document might look something like this:
<html>
<head>
<title>My Page</title>
<link rel="stylesheet"... />
<script ...jquery.js"></script>
<script ...superfish.js"></script>
<script type="text/javascript">
$('#nav').superfish({
delay:750,
speed:'fast'
});
$('#nav>li>a span').remove();
$("ul.sf-menu").superfish({
autoArrows: false
});
</script>
</head>
<body>
<ul id="nav">
<li>...
This assumes your superfish menu unordered list has an id of "nav."
