var deleteCookie = function(name) {

    document.cookie = name + '=;expires=Thu, 01 Jan 1970 00:00:01 GMT;path=/;domain=.mydomain.com;';

    document.cookie = name + '=;expires=Thu, 01 Jan 1970 00:00:01 GMT;path=/;domain=sub.mydomain.com;';

};