You can't do that with an XML processor. Your XML is not well-formed.

If you fix your XML, then you can use something like this to filter out the p's you don't want:

#!/usr/bin/perl

use strict;
use warnings;

use XML::Twig;

XML::Twig->new( twig_handlers => { 'p[@v="NO"]' => sub { $_->cut; } },
                pretty_print => 'indented',
              )
        ->parsefile( "myfile.xml")
        ->print;
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