How to Hide the "Post Thumbnail Editor" Admin Menu

function plt_hide_post_thumbnail_editor_menus() {
	//Hide the "Settings → Post Thumbnail Editor" menu.
	remove_submenu_page('options-general.php', 'pte');
}

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

Where do I put this code?