How to Hide the "myStickymenu" Admin Menu

function plt_hide_mystickymenu_menus() {
	//Hide the "Settings → myStickymenu" menu.
	remove_submenu_page('options-general.php', 'my-stickymenu-settings');
}

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

Where do I put this code?