How to Hide External files in Media Library Admin Menus

function plt_hide_external_files_in_media_library_menus() {
	//Hide the "Settings → External files in Medias Library" menu.
	remove_submenu_page('options-general.php', 'eml_settings');

	//Hide the "Media → Add external files" menu.
	remove_submenu_page('upload.php', 'efml_local_directories');
	//Hide the "Media → Directory Archives" menu.
	remove_submenu_page('upload.php', 'edit-tags.php?taxonomy=edlfw_archive&post_type=attachment');
}

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

Where do I put this code?