title: Is it possible to revoke commits?
body: <p>Assume we have a repository and 5 commits:</p>
  
  <ul>
  <li>commit 1</li>
  <li>commit 2</li>
  <li>commit 3</li>
  <li>commit 4</li>
  <li>commit 5</li>
  </ul>
  
  <p>And now I realize commits 4 and 5 are a bad idea. I want to completely remove all changes committed in commit 4 and 5. How to do it?</p>