How to Hide iThemes Sync Admin Menus

function plt_hide_ithemes_sync_menus() {
	//Hide the "Settings → iThemes Licensing" menu.
	remove_submenu_page('options-general.php', 'ithemes-licensing');
	//Hide the "Settings → iThemes Sync" menu.
	remove_submenu_page('options-general.php', 'ithemes-sync');
}

add_action('admin_menu', 'plt_hide_ithemes_sync_menus', 1000000);

Where do I put this code?