This hides a pinned if the user is logged but displays it if it's a Anonymous user

hide-pinned-topic.js

<div id="userNamewidget">
</div>
<script>
$j(document).ready(function() {

if('{{current_user.name}}' == 'Anonymous user'){ $j('div#pinned-entry-57062').show();}
else 
  { $j('div#pinned-entry-57062').hide(); }

});
</script>

create a custom widget and add the code changing the number to the number of the forum topic id