use strict;
use XML::Rules;

my $rules = XML::Rules->new(
    style => 'filter', 
    rules => {tmmTableFilenameMap => sub {}},
    namespaces => {'urn:mavenir:ns:yang:wrg-sc:6.0.2.8' => ''}
);

$rules->filter(\*DATA);

__DATA__
<sys xmlns="urn:mavenir:ns:yang:wrg-sc:6.0.2.8">
...
[download]

This doesn't load the whole file into memory which may be a big advantage.