DOMChildNode
DOMChildNode is an interface introduced in version 8.0 for DOM nodes that can have siblings. It is implemented by DOMElement, DOMText, DOMComment, DOMProcessingInstruction, and DOMDocumentType.
It provides before() and after() to insert nodes adjacent to the current node, replaceWith() to replace it, and remove() to detach it from its parent.
<?php
$dom = new DOMDocument;
$dom->loadHTML('<p>Hello <b>world</b></p>');
$b = $dom->getElementsByTagName('b')->item(0);
$b->remove();
?>