How to Hide the "LC Scripts Optimizer" Admin Menu

function plt_hide_lc_scripts_optimizer_menus() {
	//Hide the "Tools → LC Scripts Optimizer" menu.
	remove_submenu_page('tools.php', 'lcso_settings');
}

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

Where do I put this code?