function deleteCookie(name, path, domain) {
	if (getCookie(name)) {
		document.cookie = name + "=" +
			((path) ? "; path=" + path : "") +
			((domain) ? "; domain=" + domain : "") +
			"; expires=Thu, 01-Jan-70 00:00:01 GMT";
	}
}
Deletes the specified cookie.

name		name of the cookie
[path]	path of the cookie (must be same as path used to create cookie)
[domain]	domain of the cookie (must be same as domain used to create cookie)