Удаление cookies

HTML

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<p>hello!</p>
<div class="popup">
  popup text
  <span class="close">close popup</span>
</div>

CSS

.popup {
  display: none;
  width: 400px;
  height: 300px;
  padding: 20px;
  border: 3px dashed yellowgreen;
  text-align: center;
}
.show-popup .popup {
  display: block;  
}
.close {
  display: block;
  width: 200px;
  height: 40px;
  margin: 100px auto 0 auto;
  text-align: center;
  line-height: 40px;
  background: #dddddd;
  cursor: pointer;
}

JavaScript

function checkPopup() {
  if ( getCookie('popup') == 'shown' ) {
    return false;
  } else {
    showPopup();
    document.cookie = "popup=shown; path=/; expires=0";
  }
}

function showPopup() {
  $('body').addClass('show-popup');
}

function closePopup() {
  $('.close').click(function() {
    $('body').removeClass('show-popup');
  });
}

function getCookie(name) {
  var matches = document.cookie.match(new RegExp(
    "(?:^|; )" + name.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1') + "=([^;]*)"
  ));
  return matches ? decodeURIComponent(matches[1]) : undefined;
}

$(document).ready(function(){
  checkPopup();
  //showPopup();
  closePopup();
});