title: Codeigniter remove specific user's session
body: <p>In Codeigniter, how do I remove specific user's session? </p>
  
  <p>I have set login session like below. And I want to remove specific MemId's LoggedIn(in other words, session for just one user) assuming there are about 1000 users.</p>
  
  <pre><code>$this-&gt;session-&gt;set_userdata([
      'LoggedIn'=&gt;true,'MemId'=&gt;PrimaryKey
  ]);
  </code></pre>