Unlink Parent Pages in Drop-down Navigation

I want to ‘unlink’ all the parent pages (which are empty) in my drop down navigation.

The plugins I’ve looked at only work with wp_list_pages

This is the code in my header.php file for my navigation:

<div id="access" role="navigation">
<div class="menu"><li <?php if ( is_home() ) { echo ' class="current_page_item"'; } ?>>
<a href="<?php echo get_option('home'); ?>/">Home</a></li> </div>
<li><?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'primary' ) ); ?></li>

Please help!       	:flower: