title: Set `scheduledend` on Appointment to null with Javascript
body: <p>I'm writing Javascript on an Appointment form and need to clear <code>scheduledend</code>  DateTime field. </p>
  
  <p>I've tried the obvious way, but it does not work. </p>
  
  <pre class="lang-js prettyprint-override"><code>Xrm.Page.getAttribute('scheduledstart').setValue(null);
  Xrm.Page.getAttribute('scheduledend').setValue(null); // Both do nothing
  </code></pre>
  
  <p>How do I make the DateTime field blank?</p>