title: How can I 'clean up' a virtualenv?
body: <p>If I want to keep my venv as clean as possible how can I clean up the stuff I don't need? Let me lay out an example...</p>
  
  <p>Say I try a bunch of new modules...</p>
  
  <pre><code>pip install foo
  pip install bar
  pip install foobar
  pip install foobarfoo
  </code></pre>
  
  <p>and these modules have some requirements of their own, etc. later I decide on which one I want to use, but then I have a huge list of stuff in my requirement.txt and I can't remember what I need and what I don't, what depends on what, etc. </p>
  
  <p>How can I keep it clean and lean?</p>