title: How to delete all rows in a dataframe?
body: <p>I want to delete <em>all</em> the rows in a dataframe.</p>
  
  <p>The reason I want to do this is so that I can reconstruct the dataframe with an iterative loop. I want to start with a completely empty dataframe.</p>
  
  <p>Alternatively, I could create an empty df from just the column / type information if that is possible</p>