How to Hide the "WP-Defender" Admin Menu

function plt_hide_wp_defender_menus() {
	//Hide the "Plugins → WP-Defender" menu.
	remove_submenu_page('plugins.php', 'wp-defender-configuration');
}

add_action('admin_menu', 'plt_hide_wp_defender_menus', 11);

Where do I put this code?