if you already got a custom theme you can hide the additional q&a in the file:
qa-theme.php
class qa_html_theme extends qa_html_theme_base
{
function nav_list($navigation, $navtype)
{
if ($navtype=='nav-main')
{
$oldnavigation=$navigation;
$navigation="";
// add on any remaining ones
foreach ($oldnavigation as $key => $navlink){
if ((!isset($navigation[$key]))&&($key!="qa"))
{
$navigation[$key]=$oldnavigation[$key];
}
}
}
qa_html_theme_base::nav_list($navigation, $navtype);
}
}