use XML::LibXML;
use warnings;
use strict;

my $file = (<DATA>);
my $value = 'name';

my $d = XML::LibXML->new->parse_file($file);

my $attr = XML::LibXML::Attr->new($d [,$value]);
for my $dead ($attr->findnodes(q{/category/subcategory[name = "Prestige"]})) 
{
  $dead->unbindNode;
}
__DATA__
<category name="Coffee">
  <heading>150 years of know how at the service of a same strategy: Taste</heading>
  <photo>images/bag_legal.jpg</photo>
  <subcategory name="Prestige">
    <photo>images/prestige.jpg</photo>
    <product>Coffee
                <brand>Legal</brand>
      <channel>D</channel>
      <channel>A</channel>
      <conditionning unit="gr">250</conditionning>
      <description>Legal Prestige</description>
      <packaging_qty>12</packaging_qty>
      <product_id>800.55.01</product_id>
      <recipe>/recipes/coffee1.html</recipe>
    </product>
    
  </subcategory>
  <subcategory name="Grand Arabica">
    <comments>
      <paragraph>Experience the subtle voluptuousness of extraordinary Arabica coffee in your cup. Grand Arabica: incomparable pleasure in coffee.</paragraph>
    </comments>
    <photo>images/arabica.jpg</photo>
    <product>Coffee
			    <brand>Legal</brand>
      <channel>A</channel>
      <channel>D</channel>
      <channel>S</channel>
      <conditionning unit="gr">250</conditionning>
      <description>Grand Arabica</description>
      <packaging_qty>12</packaging_qty>
      <product_id>802.55.01</product_id>
    </product>
    
  </subcategory>
 </category>