<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
//function.php
function register_my_menus(){
register_nav_menus(
array(
'new-menu'=>_('leftsidebarmenu'),
'another-menu'=>_('rightsidebar'),
'an-extra-menu'=>_('An Extra Menu')
)
);
}
add_action('init','register_my_menus');
//header.php
<?php wp_nav_menu( array( 'theme_location' => 'new-menu' ) ); ?>
<style>
.sub-menu {
display:none;
}
.leftsidebar .menu-item-has-children a::after {
