title: E401 - Unable to authenticate, your authentication token seems to be invalid
body: <p>I tested with Azure Packages private NPM server and now want to revert back to using the standard NPM registry but when I do it complains.  I have tried everything I can think of and it is blocking me from doing any work now.  I'd really appreciate any help.</p>
  <p><strong>The error</strong></p>
  <ul>
  <li>npm ERR! code E401</li>
  <li>npm ERR! Unable to authenticate, your authentication token seems to be invalid.</li>
  <li>npm ERR! To correct this please trying logging in again with:</li>
  <li>npm ERR! npm login</li>
  </ul>
  <p>If I check the log it is still, somehow, trying to find packages from Azure rather than the npm registry.</p>
  <p>The Azure URL specified below doesnt exist in any .npmrc file or package-lock file I can find!</p>
  <p>To be clear here I want to use the default NPM registry not Azure. e.g.</p>
  <pre><code>32 silly fetch manifest @types/angular@https://pkgs.dev.azure.com/***/***/_packaging/***.Common.UI/npm/registry/@types/angular/-/angular-1.6.45.tgz
  </code></pre>
  <p><strong>Steps I have taken</strong></p>
  <ul>
  <li>Deleted my local .npmrc file</li>
  <li>Deleted .npmrc file from my user profile</li>
  <li>Cleared NPM cache</li>
  <li>Cleared local node_modules folder</li>
  <li>npm config set registry <a href="https://registry.npmjs.org/" rel="noreferrer">https://registry.npmjs.org/</a></li>
  <li>npm config set registry <a href="https://registry.npmjs.com/" rel="noreferrer">https://registry.npmjs.com/</a></li>
  <li>Reinstalled node.js</li>
  </ul>
  <p>In each case, running <code>npm install</code> still gives me the same error.</p>
  <p>Please help!</p>