cerca file sottocartella unlink file

<?php
function deleteFile($file) {
    if(substr($file, strlen($file)-1, 1) != '/') {
        $file .= '/';
    }
    if($handle = opendir($file)) {
        while($obj = readdir($handle)) {
            if($obj != '.' && $obj != '..') {
                if(is_dir($file.$obj)) {
                    if(!deleteFile($file.$obj)) {
                        echo $file.$obj."<br />";
                        return false;
                    }
                }
                elseif(is_file($file.$obj)) {
                    if(!unlink($file.$obj)) {
                        echo $file.$obj."<br />";
                        return false;
                    }
                }
            }
        }
        closedir($handle);
        if(!@rmdir($file)) {
            echo $file.'<br />';
            return false;
        }
        return true;
    }
    return true;
}

if ($_SERVER['REQUEST_METHOD'] == 'POST' && isset($_POST['file'])) {
$file = basename($_POST['file']);
if ($file[0] != '.') deleteFile("documenti/".$username); //qui da errore
}
?>

<form action="" method="post">
<input type="text" name="file" class="form-control" placeholder="elimina file">
<input type="submit" name="file" value="invia">
</form>