title: How to restore/reset npm configuration to default values?
body: <p>I have played with <code>npm set</code> and <code>npm config set</code> for several times, now I want to reset to default values (a kind of factory reset).</p>
  <p>Does <code>npm</code> provide a command to do that? Or should I delete all configuration files by hands then reinstall it?</p>
  <p>I need to do it both on Linux CentOS and on Windows 8.</p>