i will show you..
but i know only to put it vertical--(i dont know yet how to put 2,3 or 4collums ..i think somehow in index_box.tpl but i will try soon)

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so open functions_categories_hierarchy.php

find

$links .= (($links != '') ? ', ' : '') . $wlast_post . $link;

replace with

$links .= (($links != '') ? '<br> ' : '') . $wlast_post . $link;

find

'L_LINKS' => empty($links) ? '' : ( empty($lang['Subforums']) ? '' : '<b>' . $lang['Subforums'] . ':</b>&nbsp;' ),

replace with

'L_LINKS' => empty($links) ? '' : ( empty($lang['Subforums']) ? '' : '<b>' . $lang['Subforums'] . ':</b><br>' ),

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now open your index_box.tpl (in your folder theme !!! )

step 1
find

<span class="gensmall">{catrow.forumrow.L_LINKS}&nbsp;</span>

replace with

<span class="gensmall">{catrow.forumrow.L_LINKS}</span>

if you only want to remove title -Subforums:- from forum you dont need to make step 1
step 2
find

<span class="gensmall">{catrow.forumrow.L_LINKS}&nbsp;</span>

delete it !!

i hope this gona help somehow...

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and this how it looks with step 1

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!!!Before you do anything beckup your functions_categories_hierarchy.php and index_box.tpl !!!