Re: Remove a XML Node list
'fraid not. The DOM provides no means to remove nodes other than removeChild.
However, you might want to experiment with DocumentFragment. Using that, it should in theory be possible to remove many nodes at once. (Depending on the implementation, though, there's no guarantee that this doesn't take just as long, though.) The downside is that you first have to create the DocumentFragment, which might take just as long as deleting the nodes one by one.
What's selectNodes anyway? It's not a DOM method. Perhaps your DOM has another non-standard method called addAll(NodeList)? That would be useful.
For large XML files, you might want to look into completely different ways of processing the XML. Or perhaps you could build the DOM tree yourself using a SAX processor, filtering the undesired elements out at this level.