title: Unfork a GitHub fork without deleting
body: <p>I would like to "unfork" a GitHub fork without deleting + recreating it. Is this possible?</p>
  
  <p>My reason is that my project now has a completely different use to the source of the fork, and makes no sense to be showing number of commits ahead, or the pull request button (or at least, with such prominence). With hindsight, I think I would have just <code>git clone</code>d the original, rather than made a fork.</p>
  
  <p>I would like to not delete my fork in order to keep the issues + history of pull requests made.</p>
  
  <p>I am happy to keep the history of commits, it's just the removal of the fork status that I'm after.</p>