while (my $file = readdir ($ls)) { 
    if ( !(-d $file)){

opendir my $dh, 'directory' or die $!;
while (my $file = readdir $dh) {
  my $size = -s "directory/$file";
  ...
}

        if (unlink($file) == 0) {
            print "File $file deleted successfully.\n";
        } else {
            print "File $file was not deleted.\n";
        }