How to exclude

I’m using the following code to populate my side nav and I’m having trouble figuring out where to put the “exclude” code to hide one of the pages. Can anyone help me out?

<?php
if($post->post_parent) { // page is a child
wp_list_pages(‘sort_column=menu_order&title_li= &child_of=’.$post->post_parent);
}
elseif(wp_list_pages(“child_of=”.$post->ID.”&echo=0″) ) { // page has children
wp_list_pages(‘sort_column=menu_order&title_li= &child_of=’.$post->ID );
}
?>