Hi, To disable a menu item on the fly you should add a "disabled" attribute to the correspoding voice defined on your HTML; for example:

THIS IS THE MENU DEFINED IN THE HTML CODE:

<div id="menu_2" class="mbmenu">
    <a id="menu_2_voice_1" class="{action: 'showMessage(\'menu_2.2\')'}">menu_2.2</a>
    <a rel="separator"> </a>
    <a class="{action: 'showMessage(\'menu_2.4\')'}">menu_2.5</a>
  </div>

If you need to disable the first voice (ID: menu_2_voice_1):

<script>
    $("#menu_2_voice_1").attr("disabled",true);
</script>

Next time you'll open the menu, this voice should be disabled.

Bye, Matteo