WordPress, Disable Featured image on Single Post

gistfile1.php

/**
* Disable Featured image on Single Post
* @version: 1.0
* @author: takien
* @url: http://takien.com
* Copy and paste this code in your theme's functions.php
*/

add_filter('post_thumbnail_html','disable_single_featured');
function disable_single_featured(){
	if(is_single()){
		return false;
	}
}

/*
* if code above not work, try this one
* please use one of them, not both.
*/

add_filter('get_post_metadata', 'disable_single_featured', true, 4);
function disable_single_featured($metadata, $object_id, $meta_key, $single){
	if(is_single() AND isset($meta_key) AND ($meta_key == '_thumbnail_id')){
		return false;
	}
	else {
		return $metadata;
	}

}