If this will help:
I wanted to hide sub-subcategories from showing, so i would have only main menu tabs,
and their sub categories shown (when hover over).
in dm_categories.php find this line:
$hide_subcategories_of = array();
and enter every category id number that you don't want to show.
Follow the instructions, play around and see how it goes.
(i entered all of my sub-subcategories here)
Cheers