In menu.tpl, simply replace this:
<TD class="VertMenuTitle"> {$link_begin}<IM G src="{$ImagesDir}/{if $dingbats ne ''}{$dingbats}{else}spacer.gif{/if}" width="21" height="20" border="0" align="absmiddle">{$link_end}
{if $link_href}
<A href="{$link_href}"><FONT class="VertMenuTitle">{$menu_title}</FONT></A>
{else}
<FONT class="VertMenuBoxNewsTitle">{$menu_title}</FONT>
{/if}
</TD>
with this:
<TD class="VertMenuTitle">{$menu_title}</TD>
As for how to edit templates, custom boxes, etc. it is all here in the forums, you just need to search. I'd start with this thread:
http://forum.x-cart.com/showthread.php?t=21529
There are a few posts in the custom mods forum on how to create new menu boxes. Remember, always backup the file you are working on so you can easily restore it if you botch something up!