use XML::Twig;
use strict;
my $twig = XML::Twig->new(
    map_xmlns => {
        "http://perlmonks.org"  => 'aaa',
        "http://perlmonks.org/blah"=> 'bbb'
    },
    TwigHandlers => {
        '/aaa:monastery/aaa:foo/bbb:bar/bbb:monk' => sub { warn "matched!"; $_[0]->purge; }
    }
);

my $xml =<<XML;
<?xml version="1.0" encoding="UTF-8"?>
<prefix:monastery xmlns:prefix="http://perlmonks.org">
  <prefix:foo>
    <prefix2:bar xmlns:prefix2="http://perlmonks.org/blah">
       <prefix2:monk>Larry Wall</prefix2:monk>
    </prefix2:bar>
  </prefix:foo>
</prefix:monastery>
XML

$twig->parse($xml);