my $sel = 'title';
my $twig = XML::Twig->new(
	pretty_print => 'indented',
	twig_roots  => { "$sel" => \&parse_title },
);

$twig->parsefile('1.xml');

$twig->print;

sub parse_title {
	my ($t,$title) = @_;
	$title->delete if $title->get_xpath( 'name/fnm[@letter="a"]' );
}

##</code><code>##

<?xml version="1.0"?>
<titles>
  <title id="1">testing<name><snm>Houston</snm>, <fnm letter="c">Carl</fnm></name><g>69</g><ppg>20.1</ppg><rpg>3.4</rpg><apg>2.8</apg><blk>14</blk></title>
  <title id="3">testign
    <name>Houston
    <fnm j="b">Bob</fnm><g>49</g><title>
	testing the sub title in title
	</title><title>
	this is pcdata in subtitle
		<title>
		second sub level
		</title></title></name></title>
</titles>