'Deletes the cookie with the given name.
Due to limitations of the cookie protocol, you must pass the same
path and domain to clear a cookie as were used when that cookie
was set (but there is no way to find out on the server side
which values were used for a given cookie).
Similar to `set_cookie`, the effect of this method will not be
seen until the following request.'

def clear_cookie(self, name, path='/', domain=None):

    expires = (datetime.datetime.utcnow() - datetime.timedelta(days=365))
    self.set_cookie(name, value='', path=path, expires=expires, domain=domain)
