How to customize wordpress menu ?

Use below code

<?php 
function clean_custom_menu( $theme_location ) {
    if ( ($theme_location) && ($locations = get_nav_menu_locations()) && isset($locations[$theme_location]) ) {
        $menu = get_term( $locations[$theme_location], 'nav_menu' );
        $menu_items = wp_get_nav_menu_items($menu->term_id);
  
        $menu_list  = '<div class="tbns">' ."\n";
 
        $count = 0;
        $submenu = false;
         
        foreach( $menu_items as $menu_item ) {
             
            $link = $menu_item->url;
            $title = $menu_item->title;
             
            if ( !$menu_item->menu_item_parent ) {
                $parent_id = $menu_item->ID;
                 
                $menu_list .= '<div class="col-f-5"><ul class="item">' ."\n";
                $menu_list .= '<li><a href="'.$link.'" class="title">'.$title.'</a></li>' ."\n";
            }
 
            if ( $parent_id == $menu_item->menu_item_parent ) {
 
                if ( !$submenu ) {
                    $submenu = true;
                    $menu_list .= '' ."\n";
                }
 
                $menu_list .= '<li class="item">' ."\n";
                $menu_list .= '<a href="'.$link.'" class="title">'.$title.'</a>' ."\n";
                $menu_list .= '</li>' ."\n";
                     
 
                if ( $menu_items[ $count + 1 ]->menu_item_parent != $parent_id && $submenu ){
                    $menu_list .= '' ."\n";
                    $submenu = false;
                }
 
            }
 
            if ( $menu_items[ $count + 1 ]->menu_item_parent != $parent_id ) { 
                $menu_list .= '</ul></div>' ."\n";      
                $submenu = false;
            }
 
            $count++;
        }
         
        $menu_list .= '</div>' ."\n"; 
 
    } else {
        $menu_list = '<!-- no menu defined in location "'.$theme_location.'" -->';
    }
    echo $menu_list;
}

In page

clean_custom_menu('primary');