title: Pandas Error: '[nan nan] not found in axis' while dropping a column without labels
body: <p>I'm trying to drop the first two columns in a dataframe that has NaN for column headers. The dataframe looks like this:</p>
  <pre><code>**15 NaN NaN          NaN           Energy Supply  Energy Supply Renewable Energy**
    17 NaN Afghanistan  Afghanistan   1              2             3
    18 NaN Albania      Albania       1              2             3
    19 NaN Algeria      Algeria       1              2             3
    
  </code></pre>
  <p>I need to drop the first two columns labeled NaN. I tried <code>df=df.drop(df.columns[[1,2]],axis=1)</code>, which returns an error
  What am I missing?</p>
  <blockquote>
  <p>KeyError: '[nan nan] not found in axis'</p>
  </blockquote>