title: How to remove all html tags except bold, italic, underline and new line?
body: <p>I am not that good with regular expression so I am seeking help for this one.</p>
  
  <p>I would like to know what is a regular expression for removing all html tags except for the following.</p>
  
  <ol>
  <li>Bold</li>
  <li>Italic</li>
  <li>Underline</li>
  <li>New Line <br></li>
  </ol>
  
  <p>Thanks guys. hope you could help me on this one.</p>