removeChild

[ojalà]

Hi! I need help with removeChild function.
This is my xml file:

<ROOT>
<RT xml:id="1">
<str name="title">aaaa</str>
<str name="date">aaaa</str>
</RT>
<RT xml:id="2">
<str name="title">aaaa</str>
<str name="date">aaaa</str>
</RT>
<RT xml:id="3">
<str name="title">aaaa</str>
<str name="date">aaaa</str>
</RT>
</ROOT>

I need to remove RT node (not all RT node, only RT with a specific id, for examlpe id=2) and it's child.
I use this code to remove RT child but I'm unable to remove parent (RT with id=2). Help please..
$elem = $xml->getElementById($idElement);
$num = $elem->childNodes->length;
for ($k = 0; $k < $num; $k++)
{$childNode = $elem->removeChild($elem->childNodes->item($k));}
$xml->saveXML();

[ojalà]

any idea??