Removing an element form XML file in PHP - php

Question

i tried to find it out with previous answers but i cannot do it propperly, i followed Stefan's answer Remove a child with a specific attribute, in SimpleXML for PHP
and my code is
xml:
<?xml version="1.0" encoding="utf-8"?>
<res>
<items>
<item>
<id>1</id>
<a>asdasda</a>
</item>
<item>
<id>1</id>
<a>bababba</a>
</item>
<id>2</id>
<a>sasdasda</a>
</item>
<item>
<id>3</id>
<a>sasdasda</a>
</item>
<item>
<id>4</id>
<a>sasdasda</a>
</item>
<item>
<id>5</id>
<a>sasdasda</a>
</item>
<item>
<id>6</id>
<a>sasdasda</a>
</item>
</items>
</res>
and php is
<?php
$id="1";
$xml = simplexml_load_file("filtracjaxml.xml") ;
foreach($xml->items->item->id as $id)
{
if($id == '1') {
$xml=dom_import_simplexml($id);
$xml->parentNode->removeChild($xml);
}
}
echo $xml->asXml();
?>
when i try to run it i have
Fatal error: Call to undefined method DOMElement::asXml() in filtruj.php on line 14
EDIT:
What I want is deleting the whole 'item' not only 'id' - all items with id = 1
so i changed the code :
foreach ( $xml->items->item as $id )
{
if ( $id->id == '1' ) {
$tmp = dom_import_simplexml($id);
$tmp->parentNode->removeChild($tmp);
}
}
echo $xml->asXml();
and it deletes only the first item. Could you tell me why? what is wrong in the code written above?

Answer 1

<?php
$id="1";
$xml = simplexml_load_file("filtracjaxml.xml") ;
foreach ( $xml->items->item->id as $id )
{
if ( $id == '1' ) {
$tmp = dom_import_simplexml($id);
$tmp->parentNode->removeChild($tmp);
}
}
echo $xml->asXml();
?>