How to Hide WL Katalogsøk Admin Menus

function plt_hide_inter_library_search_by_webloft_menus() {
	//Hide the "Tools → WL Katalogsk" menu.
	remove_submenu_page('tools.php', 'wl_katalogsok_tools');
	//Hide the "Settings → WL Katalogsk" menu.
	remove_submenu_page('options-general.php', 'wl_katalogsok_options');
}

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

Where do I put this code?