I'm trying to figure out how to unregister 4 nav menus from a WordPress theme via it's functions.php file.

The parent theme is registering them by:
PHP Code:
register_nav_menus( array(
'top-menu'        => __'Top Menu''responsive' ),
'header-menu'     => __'Header Menu''responsive' ),
'sub-header-menu' => __'Sub-Header Menu''responsive' ),
'footer-menu'     => __'Footer Menu''responsive' )
I've tried a couple different combinations of things looking at the WordPress Codex, but it doesn't dive into depth with how to unregister a menu. And a Google search turned up less results than I imagined it would. I guess I'm still not able to wrap my head around how to implement the function to remove these menus in particular.