If I have read your question correctly, the following should work:
<?php
$FileName = "uploaded_file"
if (unlink($FileName))
{
echo ("$FileName has been deleted successfully. ");
}
else
{
echo ("The uploaded file has NOT been deleted.");
}
?>
If it does not. You will have to change the ownership of the files during upload.
chmod($FileName, 0755);