title: How to undo a 301 redirect?
body: <p>Now, I don't have any problems with 301 redirects, but one person asked me for the way to undo cached 301 redirects for browsers and search engines, so I replied "by doing a 301 redirect back to the original url", at least thats what I thought was the solution, until I saw people mentioning that you can't do a 301 redirect back
  <a href="http://getluky.net/2010/12/14/301-redirects-cannot-be-undon/" rel="noreferrer">http://getluky.net/2010/12/14/301-redirects-cannot-be-undon/</a>
  <a href="http://www.velocityreviews.com/forums/t500058-undo-301-redirect.html" rel="noreferrer">http://www.velocityreviews.com/forums/t500058-undo-301-redirect.html</a></p>
  
  <p>this was a surprise and I don't know for sure if it's true, so what I'm asking is, what would be the <em>proper</em> way to revert a cached permanent 301 redirect from page /a.html to page /b.html back to the original /a.html ?</p>
  
  <p>I would like some experts opinions.</p>