I know this thread has been answered, but another solution that may be useful for some, particularly to those with multiple pages where they want to have this button, is to give the input an id and place the code in a JavaScript file. You can then place the code for the button on multiple pages, taking up less space in your code.
For the button:
<input type="button" id="cancel_edit" value="Cancel"></input>
in the JavaScript file:
$("#cancel_edit").click(function(){
window.open('','_parent','');
window.close();
});