title: How to delete the same words in each row of a column?
body: <p>I have a dataframe <code>df</code>:</p>
  
  <pre><code>        workhours
  0       0 days 01:45:13.250000000
  1       0 days 04:23:56.723404255
  2       0 days 07:11:01.688888888
  3       0 days 06:02:48.160000000
  4       0 days 06:27:57.280000000
  5       0 days 07:00:26.551020408
  6       0 days 09:04:01.039215686
  7       0 days 08:50:11.941176470
  8       0 days 07:30:59.725490196
  ...
  </code></pre>
  
  <p>And I just want to have the hours and not the "= days".
  How can I delete this from each row?</p>