title: Delete all rows from table except one with <th> tags
body: <p>If I have table with id="tbl_users" and I have</p>
  
  <pre><code>&lt;tr&gt;
     &lt;th&gt;name&lt;/th&gt;
     &lt;th&gt;username&lt;/th&gt;
     &lt;th&gt;password&lt;/th&gt;
  &lt;/tr&gt;
  </code></pre>
  
  <p>and bellow I append data. How to empty table ( delete all rows with darta) before reloading users, but not to delete row with  ? I use JQuery in project.</p>