Dude, you can't, but you can find all the website are a linking your site, and send a request and tell them delete the link
you should appreciate the link your website

You can't prevent anyone from linking to your website, but you can limit the amount of time someone can view the link. One method would be to include a limited time-hash that would give the distributed link a small amount of time which it can be viewed if a user follows it from an external source.

$file="foo.mp3";
$salt="youpeskykids";
$expiry=time()+3600;
$hash=md5($salt.$file.$expiry);

$url="download.php?file=$file&e=$expiry&h=$hash";