Custom post type is display a separator

Hi, I just created a custom post type (based on the Bones starter theme template). Everything is ok except that the admin tab printed add a separator and I don’t know how to search for deleting it.
Here’s my custom post code:

// let's create the function for the custom type
function custom_post_example() {
	// creating (registering) the custom type
	register_post_type( 'custom_type', /* (https://codex.www.ads-software.com/Function_Reference/register_post_type) */
		// let's now add all the options for this post type
		array( 'labels' => array(
			'name' => __( 'Prodotti', 'ali' ), /* This is the Title of the Group */
			'singular_name' => __( 'Prodotto', 'ali' ), /* This is the individual type */
			'all_items' => __( 'Tutti i prodotti', 'ali' ), /* the all items menu item */
			'add_new' => __( 'Aggiungi nuovo', 'ali' ), /* The add new menu item */
			'add_new_item' => __( 'Aggiungi un nuovo prodotto', 'ali' ), /* Add New Display Title */
			'edit' => __( 'Modifica', 'ali' ), /* Edit Dialog */
			'edit_item' => __( 'Modifica prodotto', 'ali' ), /* Edit Display Title */
			'new_item' => __( 'Nuovo prodotto', 'ali' ), /* New Display Title */
			'view_item' => __( 'Visualizza prodotto', 'ali' ), /* View Display Title */
			'search_items' => __( 'Cerca prodotto', 'ali' ), /* Search Custom Type Title */
			'not_found' =>  __( 'Nothing found in the Database.', 'ali' ), /* This displays if there are no entries yet */
			'not_found_in_trash' => __( 'Nothing found in Trash', 'ali' ), /* This displays if there is nothing in the trash */
			'parent_item_colon' => ''
			), /* end of arrays */
			'description' => __( 'This is the example custom post type', 'ali' ), /* Custom Type Description */
			'public' => true,
			'publicly_queryable' => true,
			'exclude_from_search' => false,
			'show_ui' => true,
			'query_var' => true,
			'menu_position' => 3, /* this is what order you want it to appear in on the left hand side menu */
			'menu_icon' => 'dashicons-list-view',
			'rewrite'	=> array( 'slug' => 'prodotto', 'with_front' => false ), /* you can specify its url slug */
			'has_archive' => 'custom_type', /* you can rename the slug here */
			'capability_type' => 'post',
			'hierarchical' => false,
			'supports' => array( 'title', 'editor', 'thumbnail', 'custom-fields', 'revisions', 'sticky')
		) /* end of options */
	); /* end of register post type */
}

And here you can see how it display the additional separator.

Thank you for your help