title: How to hard delete an orphan commit in git?
body: <p>I have local commit that are not on any branch that I would like to delete.
  I don't want to rebase them, I really want to delete them, and loose all the content related to these commit.</p>
  
  <p>Is their a command to do so ?</p>
  
  <p>So far I've tried interactive rebase as many suggested, but it just move commit around, it doesn't delete them. I've also tried to use reflog delete, but I can't figure out how to pass a specific commit Id to the command.</p>
  
  <p>Here's the working tree:</p>
  
  <pre><code>o [master] Commit #6  
  |  
  o Commit #5  
  |  
  | o Commit #4  
  |/  
  o Commit #3  
  |  
  o Commit #2  
  |  
  o Commit #1  
  </code></pre>
  
  <p>I want to physically delete the commit #4.</p>