Code
<script type="text/javascript">
link=document.getElementsByTagName('a');
hideForums=new Array('1.sub-forum','2.sub-forum','3.sub-forum'); // hidden forums
for(k=0;k<hideForums.length;k++){
for(i=0;i<link.length;i++){
if(link[i].className=='forum' && link[i].innerHTML==hideForums[k]){
link[i].parentNode.parentNode.style.display='none';
}}}
</script>
This code go's after $BODY$ in General appearance of forum pages
Where are 1.sub-forum, 2.sub-forum, and so on is a hidden forums in your forum list, so the name of forums must be the same
For example if you have a forum called Games and Music then your code will be
Code
<script type="text/javascript">
link=document.getElementsByTagName('a');
hideForums=new Array('Games','Music'); // hidden forums
for(k=0;k<hideForums.length;k++){
for(i=0;i<link.length;i++){
if(link[i].className=='forum' && link[i].innerHTML==hideForums[k]){
link[i].parentNode.parentNode.style.display='none';
}}}
</script>
Now Game and Music will be hidden and now you make a new forum called Whatever And you make a description for this forum Whatever like this
Code
Sub-forums:<br><a href="http://LINK-TO_GAMES_FORUM.com">Games</a> -<a href="http://LINK-TO_MUSIC_FORUM.com">Music</a><br>
So now this 2 forums will be like a sub-forums!