Tryit Editor v1.8

Source Code:

<!DOCTYPE html>
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
<script>
$(document).ready(function(){
  $("button").click(function(){
    $("p").removeAttr("id class");
  });
});
</script>
<style type="text/css">
#p1
{
color:white;
background-color:green;
font-size:20px;
padding:5px; 
}
.blue
{
color:white;
background-color:blue;
font-size:20px;
padding:5px; 
}
</style>
</head>
<body>

<h1>This is a heading</h1>
<p id="p1">This is a paragraph.</p>
<p class="blue">This is another paragraph.</p>

<button>Remove id and class attribute from all p elements</button>

</body>
</html>

Result:

W3Schools.com - Try it yourself

Edit the code above and click "Submit Code" to see the result.