title: Discover and remove all deleted files from git history
body: <p>Here is the problem:</p>
  
  <p>I have a github repo that was full of unwanted data and I decided to move them aside and leave there only my code there, as this is considered a best practice.</p>
  
  <p>My problem was that it took too much time to clone or to change and commit a very small file.
  Now that I have deleted all my data, I would like to erase them from the history of github, so that my repo becomes <strong>small</strong> again.</p>
  
  <p>I've been trying various solution and none has worked.
  My problem is that I really don't know what files I have removed, but I just know that I want to delete the history of <strong>all files</strong> that have been <strong>deleted</strong> from my repo until now.</p>
  
  <p>Is there an easy way to do this? I guess it's a very basic and elementary problem, so a solution must exist.</p>
  
  <p>Thanks in advance.</p>