title: how to delete multiple columns in one pass
body: <p>How can I delete multiple columns in one pass? I know this works</p>
  
  <pre><code>del df['A']
  del df['B']
  </code></pre>
  
  <p>but</p>
  
  <pre><code>del df[['A', 'B']]
  </code></pre>
  
  <p>doesn't.</p>