controlling ownership on file uploads ...

Greetings. I've written a simple form to allow my clients to upload files to me, and it works fine EXCEPT that the uploaded file is owned by "www" and I while I can read the file, I don't have the necessary permissions to delete it when done ... Since this site is being hosted elsewhere, is there a way I can control ownership so that I can delete the file? I've written my ISP/web hoster and received no response -- usually that's their subtle way of telling me I should ask the PHP quiestion here :-) Any and all help would be appreciated. Thanks, kenn