How to Hide the "Picnote" Admin Menu

function plt_hide_picnote_image_annotations_menus() {
	//Hide the "Settings → Picnote" menu.
	remove_submenu_page('options-general.php', 'picnote-settings');
}

add_action('admin_menu', 'plt_hide_picnote_image_annotations_menus', 1000000000);

Where do I put this code?