[rackit]

In categories.tpl:

replace:

{section name=cat_num loop=$categories}
<font class=CategoriesList>{ $categories[cat_num].category_name|escape }</font>

{/section}

with:

{section name=cat_num loop=$categories}
{if $categories.[cat_num].categoryid eq '###'}{

}
{else} 
<font class=CategoriesList>{ $categories[cat_num].category_name|escape }</font>

}{/if}
{/section}