remove category bar

probably in header.php (depending on your theme) you will find a line with wp_list_categories('title_li=') (or some other stuff in the brackets)

some code like this:

<div id="menu2"><ul id="rmenu" class="clearfix rMenu-hor rMenu"><?php wp_list_categories(......); ?>
</ul></div>

remove this code.

before editing theme files, make a backup of your theme