Dear xaby,
If you want to disable the current menu,Just go to the templates/ja_rasite/layouts/blocks/mainnav.php and remove this
<div id=”ja-mainnav” class=”wrap”>
<div class=”main clearfix”>
<?php if (($jamenu = $this->loadMenu())) $jamenu->genMenu ($this->getParam(‘startlevel’,0), $this->getParam(‘endlevel’,-1)); ?>
</div>
</div>
<?php if ($this->hasSubmenu() && ($jamenu = $this->loadMenu())) : ?>
<div id=”ja-subnav” class=”wrap”>
<div class=”main clearfix”>
<?php $jamenu->genMenu (1); ?>
</div>
</div>
<?php endif;?>
You also can creating a new module position then assign the menu module you want to use on that position .