Disable custom script

I’m using the ClickDesk system by inserting their code into my themes admin panel which has an option for custom code.

It works fine, but we want to disable the code for administrators, but nothing I have tried is working.

Here’s the code I tried without any luck.

if ( !is_admin() ) {
<!-- ClickDesk Live Chat Service for websites -->
<script type='text/javascript'>
etc etc etc etc
</script>
<!-- End of ClickDesk -->

}

Thanks for any help!