KILL the cookie for PW protected pages / posts

[coreystovin]

I did some searching and found this idea. http://wordpress.org/support/topic/190190

I want wordpress to automatically delete the cookie it creates on user's computers after they leave the page, close the browser window... Or like in the example above which would be sufficient adds a time-out for 10sec... than the user will have to re-enter the password to regain access.

So the info says to :
Change in wp-pass.php the follow code, on line 16:

setcookie('wp-postpass_' . COOKIEHASH, $_POST['post_password'], time() + 864000, COOKIEPATH);

You need to change the value of 864000 seconds, according to yours users needed.

In my site, i just need to remember the cookie 10 seconds.

So it should be as:

setcookie('wp-postpass_' . COOKIEHASH, $_POST['post_password'], time() + 10, COOKIEPATH);


If this should work where do I find wp-pass.php ? I can't seem to see it under Appearance->Editor.