Remove unwanted elements for a wp_nav_menu

Question

I am working on building a custom mega menu within Wordpress.I am running into an issue with unwanted elements being displayed from wp_nav_menu which are distorting my menu.

<?php
    wp_nav_menu( array(
       'theme_location' => 'main-menu',
       'menu_id'            => 'primary-menu',
       'items_wrap'     => '<ul class="nav-menu row">%3$s</ul>',
       'walker'         => new custom_menu,
       'container'         => 'false',
       'menu_class'        => 'false',
    ) );
 ?>

I am calling a custom walker so I can display certain div and order list, which is the following:

class custom_menu extends Walker_Nav_Menu {
function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
    $output .= "\n$indent<ul><div class=\"container\">\n";
}
function end_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
    $output .= "$indent</ul></div>\n";
}
}
 add_filter('nav_menu_css_class', 'my_css_attributes_filter', 100, 1);
 add_filter('nav_menu_item_id', 'my_css_attributes_filter', 100, 1);
 add_filter('page_css_class', 'my_css_attributes_filter', 100, 1);
 function my_css_attributes_filter($var) {
   return is_array($var) ? array_intersect($var, array('sub-menu-columns')) : '';
}

and below is the HTML it is displaying. I also marketed the elements I need to remove.

 <div class="menu">
    <ul class="nav-menu row">
        <li><a href="http://dccollegenew.wpengine.com/admission-aspx/">Admissions and Aid</a>
            <ul>
                <li style="list-style: none; display: inline"><!-- REMOVE -->
                    <div class="container">
                        <ul><!-- REMOVE -->
                            <li><h2>Admissions</h2>
                                <div class="menu-admissions-delivery-systems-container"><!-- REMOVE -->
                                    <ul class="menu" id="menu-admissions-delivery-systems"><!-- REMOVE CLASS AND ID-->
                                        <li><a href="http://dccollegenew.wpengine.com/freshmen-admissions/">Freshmen Admissions</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/transfer/">Transfer Admissions</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/online-courses/">Online Programs</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/adult-programs/">Adult Students</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/graduate-admissions/">Graduate Admissions</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/international-students/">International Students</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/veterans/">Veterans and Military Students</a></li>
                                    </ul>
                                </div><!-- REMOVE -->
                            </li>
                            <li>
                                <h2>Financial Aid</h2>
                                <div class="menu-admissions-financial-aid-container"><!-- REMOVE -->
                                    <ul class="menu" id="menu-admissions-financial-aid"><!-- REMOVE CLASS AND ID-->
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/">Financial Aid</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/scholarship-financial-aid-options/">Scholarship and Financial Aid Options</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/financial-aid-forms/">Financial Aid Forms</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/contact-financial-aid-counselor/">Contact a Financial Aid Counselor</a></li>
                                        <li><a href="http://dccollegenew.wpengine.com/admissions/financial-aid-2/net-price-calculator/">Net Price Calculator</a></li>
                                    </ul>
                                </div><!-- REMOVE -->
                            </li>
                        </ul><!-- REMOVE -->
                    </div>
                </li>
            </ul>
        </li>
    </ul>
</div>

This is how the menu should display

 <section class="bottom-header container-fluid">
 <div class="menu">
    <ul class="clearfix nav-menu">
        <li><a href="#">Admissions and Aid</a>
            <ul>
                <div class="container">
                    <li><h2>School</h2>
                        <ul>
                            <li><a href="#">Lidership</a></li>
                            <li><a href="#">History</a></li>
                            <li><a href="#">Locations</a></li>
                            <li><a href="#">Careers</a></li>
                        </ul>
                    </li>
                    <li><h2>School</h2>
                        <ul>
                            <li><a href="#">Undergraduate</a></li>
                            <li><a href="#">Masters</a></li>
                            <li><a href="#">International</a></li>
                            <li><a href="#">Online</a></li>
                        </ul>
                    </li>
                    <li><h2>School</h2>
                        <ul>
                            <li><a href="#">Undergraduate research</a></li>
                            <li><a href="#">Masters research</a></li>
                            <li><a href="#">Funding</a></li>
                        </ul>
                    </li>
                    <li><h2>School</h2>
                        <ul>
                            <li><a href="#">Undergraduate research</a></li>
                            <li><a href="#">Masters research</a></li>
                            <li><a href="#">Funding</a></li>
                        </ul>
                    </li>
                </div>
            </ul>
        </li>
        <li><a href="#">Academics</a></li>
        <li><a href="#">Student Life</a></li>               
        <li><a href="#">Athletics</a></li>  
        <li><a href="#">Alumni</a></li>
        <li><a href="#">About Us</a></li>
        <li><a href="#">Support The College</a></li>
    </ul>
 </div>
 </section>

No matter what I do I can't seem to remove those items I have labeled remove. Any help would be greatly appreciated.

Answer 1

I got it to work by reconfiguring the walker

 class custom_menu extends Walker_Nav_Menu {
   function start_el(&$output, $item, $depth, $args) {
    global $wp_query;
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

    $class_names = $value = '';

    $classes = empty( $item->classes ) ? array() : (array) $item->classes;

    $class_names = join( ' ', apply_filters( 'nav_menu_css_class',  array_filter( $classes ), $item ) );
    $class_names = ' class="' . esc_attr( $class_names ) . '"';

    $output .= $indent . '<li>';

    $attributes = ! empty( $item->attr_title ) ? ' title="' . esc_attr( $item->attr_title ) .'"' : '';
    $attributes .= ! empty( $item->target ) ? ' target="' . esc_attr( $item->target ) .'"' : '';
    $attributes .= ! empty( $item->xfn ) ? ' rel="' . esc_attr( $item->xfn ) .'"' : '';
    $attributes .= ! empty( $item->url ) ? ' href="' . esc_attr( $item->url ) .'"' : '';

    $item_output = $args->before;
    $item_output .= '<a'. $attributes .'>';
    $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
    $item_output .= '</a>';
    $item_output .= $args->after;

    $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
}
function start_lvl(&$output, $depth) {
    $indent = str_repeat("\t", $depth);
    $output .= "\n$indent<ul><div class=\"container\">\n";
  }
 }
  add_filter('nav_menu_css_class', 'my_css_attributes_filter', 100, 1);
  add_filter('nav_menu_item_id', 'my_css_attributes_filter', 100, 1);
  add_filter('page_css_class', 'my_css_attributes_filter', 100, 1);
    function my_css_attributes_filter($var) {
    return is_array($var) ? array_intersect($var, array('sub-menu-columns'))    : '';
 }