title: How to remove a XMLNode from XMLDocument occuring at multiple nested levels
body: <p>I have a XML which has a node which kind of gets repeated across multiple levels in the file using C#. </p>
  
  <p>Example of the XML: </p>
  
  <pre><code>&lt;books&gt;
      &lt;book&gt;
          &lt;title&gt;The Walking Dead&lt;/title&gt;
          &lt;author&gt;Test Name&lt;/author&gt;
          &lt;isbn&gt;1239859895&lt;/isbn&gt;
      &lt;/book&gt;
      &lt;book&gt;
          &lt;title&gt;The Walking Dead&lt;/title&gt;
          &lt;author&gt;
              &lt;isbn&gt;29893893893&lt;/isbn&gt;
              &lt;firstname&gt;test1&lt;/firstname&gt;
              &lt;lastname&gt;test&lt;/lastname&gt;
          &lt;/author&gt;
      &lt;/book&gt;        
  &lt;/books&gt;
  </code></pre>
  
  <p>I want to remove all <em>isbn</em> nodes from this XMLdocument irrespective of its location. </p>