title: git remove a commit from pull request
body: <p>I'm newbie to open source contribution, so it one of my first tries.</p>
  
  <p>I developed a library (gem) called <code>validates</code>: <a href="https://github.com/kaize/validates/">https://github.com/kaize/validates/</a></p>
  
  <p>I made 2 branches through <code>git checkout -b branch_name</code>:</p>
  
  <p>https://github.com/kaize/validates/pull/20 &amp; https://github.com/kaize/validates/pull/19, and make commits for them, but, you can see that ip-validator pull request have a commit <code>Blank validator</code> <code>399cdd7</code>.</p>
  
  <p>What I need to do to remove it from this pull request (and still place in blank validator branch)?</p>
  
  <p>Please help me with make world better, guys!</p>