custom menu being displayed on admin page

I am trying to create a theme for wordpress and created a custom menu and sidebar for the theme. However, for the custom menu, it appears inside the admin page as the picture shown. Can I know why this is happening and how to make it only display on the page itself? Thanks inn advance.

My code for the custom sidebar and menu:

function custom_menu() {
$args = array(
    'theme_location'  => '',
    'menu'            => '',
    'container'       => 'div',
    'container_class' => '',
    'container_id'    => '',
    'menu_class'      => 'menu',
    'menu_id'         => '',
    'echo'            => true,
    'fallback_cb'     => 'wp_page_menu',
    'before'          => '',
    'after'           => '',
    'link_before'     => '',
    'link_after'      => '',
    'items_wrap'      => '<ul id="%1$s" class="%2$s">%3$s</ul>',
    'depth'           => 0,
    'walker'          => ''
    );

wp_nav_menu($args);
register_nav_menu( 'primary', 'primary_menu');}


function custom_sidebar()  {
$args = array(
    'id'            => 'sidebar_nav',
    'name'          => __( 'Sidebar', 'text_domain' ),
    'description'   => __( 'Sidebar Description', 'text_domain' ),
    'class'         => '',
    'before_title'  => '<h2 class="widgettitle">',
    'after_title'   => '</h2>',
    'before_widget' => '<li id="%1$s" class="widget %2$s">',
    'after_widget'  => '</li>',
);

register_sidebar( $args );}

add_action( 'widgets_init', 'custom_sidebar' );?>