title: How to delete rows from .csv files
body: <p>I need to remove rows from my .csv file in order to compare files for changes day over day ideally using python. I need to delete the first 3 rows as well as the line which begins with "Not Classified". I wrote an excel macro that does exactly that, but I have close to 1000 files that need modifying and the fairly simple script was taking over 1 hr to complete (mostly due to saving each file) and so I am looking for something more efficient or at the bare minimum something that doesn't preclude me from using excel while the script runs.</p>
  
  <p>Here is basically my file,</p>
  
  <pre><code>Date MM/DD/YYYY,,,,,,,
  Start Time XX:XX,,,,,,,
  Completed YY:YY,,,,,,,
  A,b,c,d,e,f
  g,h,i,j,k,l
  1,2,3,4,5,6
  ,,,,,,,,,,,
  ,,,,,,,,,,,
  ,,,,,,,,,,,
  Not Classified,,,,,,,
  ,,,,,,,,,,,
  </code></pre>
  
  <p>My output should simply look like</p>
  
  <pre><code>A,b,c,d,e,f
  g,h,i,j,k,l
  1,2,3,4,5,6
  ,,,,,,,,,,,
  ,,,,,,,,,,,
  ,,,,,,,,,,,
  </code></pre>
  
  <p>Thanks in advance</p>