title: conda: remove all installed packages from base/root environment
body: <h2>TL:DR: How can I remove all installed packages from <code>base</code>?</h2>
  <p>I installed a bunch of machine learning packages in my <code>base</code> conda environment.</p>
  <p>I've now created a <code>ml</code> environment for machine learning, and wish to reset my <code>base</code> environment by removing all the packages installed there.</p>
  <p>I've tried:</p>
  <pre><code>% activate base
  % conda uninstall -n base --all
  
  CondaEnvironmentError: cannot remove current environment. deactivate and run conda remove again
  </code></pre>
  <p>Apparently, I can't remove packages from the current environment(?!), so lets switch to my <code>ml</code> environment first:</p>
  <pre><code>% source activate ml
  % conda uninstall -n base --all
  
  CondaEnvironmentError: cannot remove root environment,
         add -n NAME or -p PREFIX option
  </code></pre>
  <p>Orright, I'll use <code>-p</code> then...</p>
  <pre><code>% conda uninstall -p ~/.local/share/miniconda3 --all
  
  CondaEnvironmentError: cannot remove root environment,
         add -n NAME or -p PREFIX option
  </code></pre>
  <p>How do I uninstall all installed packages in the <code>base</code> or <code>root</code> environment?</p>