How to Hide Portfolio Post Type Admin Menus

function plt_hide_portfolio_post_type_menus() {
	//Hide "Portfolio".
	remove_menu_page('edit.php?post_type=portfolio');
	//Hide "Portfolio → All Portfolio Items".
	remove_submenu_page('edit.php?post_type=portfolio', 'edit.php?post_type=portfolio');
	//Hide "Portfolio → Add New Portfolio Item".
	remove_submenu_page('edit.php?post_type=portfolio', 'post-new.php?post_type=portfolio');
	//Hide "Portfolio → Portfolio Categories".
	remove_submenu_page('edit.php?post_type=portfolio', 'edit-tags.php?taxonomy=portfolio_category&post_type=portfolio');
	//Hide "Portfolio → Portfolio Tags".
	remove_submenu_page('edit.php?post_type=portfolio', 'edit-tags.php?taxonomy=portfolio_tag&post_type=portfolio');
}

add_action('admin_menu', 'plt_hide_portfolio_post_type_menus', 15);
Where do I put this code?