ZipArchive::deleteIndex

I'm trying to delete file using deleteName and deleteIndex, it returns true but files are not removed. can anybody tell me how could it be?

Here is code snippet

$zip = new ZipArchive ;
$zipname = "www.zip" ;
chmod( $zipname, 0777 ) ;

if ( $zip->open( $zipname ) )
{
     $loop = $zip->numFiles ;
    for ( $i = 0; $i < $loop; $i++ )
    {
        
        var_dump($zip->deleteIndex( $i )) ;
        var_dump(deleteName($zip->getNameIndex( $i )). "/") ;

    } 
}$zip->close() ;