WordPress Version: .10
/**
* Unregisters a meta key for posts.
*
* @since 4.9.8
*
* @param string $post_type Post type the meta key is currently registered for. Pass
* an empty string if the meta key is registered across all
* existing post types.
* @param string $meta_key The meta key to unregister.
* @return bool True on success, false if the meta key was not previously registered.
*/
function unregister_post_meta($post_type, $meta_key)
{
return unregister_meta_key('post', $meta_key, $post_type);
}