'Unset a cookie in the response
Clears the contents of the cookie, and instructs the user
agent to immediately expire its own copy of the cookie.
Warning:
In order to successfully remove a cookie, both the
path and the domain must match the values that were
used when the cookie was created.'

def unset_cookie(self, name):

    if (self._cookies is None):
        self._cookies = SimpleCookie()
    self._cookies[name] = ''
    self._cookies[name]['expires'] = (-1)
