use XML::LibXML 2;
use XML::LibXML::PrettyPrint 'print_xml';

my $xml = XML::LibXML->load_xml(IO => \*DATA);

# Promote <arit> elements out of their <z> container
$xml
	-> findnodes('//z/arit')
	-> foreach(sub { $_->parentNode->parentNode->appendChild($_) });

# Remove certain elements
$xml
	-> findnodes('//z | //runhd | //i-g | //zp_pvg | //zp_cl | //ar | //zp_gr')
	-> foreach(sub { $_->parentNode->removeChild($_) });

print_xml $xml;

__DATA__
<entry rootUID="281088" Class="A" Name="abc"><h-g><h>abc</h><runhd>abc</runhd>
<z>/</z><i-g><i>abc123</i></i-g><z>/</z></h-g><zp_pvg /><pv-g>
<pv>abc is 123</pv><z> (</z><r r="REG" /><z><it2>Reg</it2>) </z>
<d tranID="1" status="3">abc is a company.<chn localeUID="202" status="3"
>(Chinese translation)</chn></d><z>: </z><x tranID="2" status="3"
>abc launched in 1992.<chn localeUID="202" status="3"
>Some other Chinese translation</chn></x><obj-g><zp_cl />
<z>Symbolmark</z><cl>rules</cl><ar>, </ar><cl>decision</cl><ar>, </ar>
<cl>the law</cl><z>Another Symbol</z><syn>Something </syn><cf>(positive)</cf>
</obj-g><zp_gr /><z>some symbol</z><gr-g><gr gr="P" /><z><arit>1+1=3</arit>
</z></gr-g></pv-g></entry>