Python 带 cookie 模拟登录切换多个帐号时，该如何清除 cookie？

import cookielib

import urllib2 import cookielib

filename = 'cookie.txt'

cookie = cookielib.MozillaCookieJar(filename) opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cookie)) postdata = urllib.urlencode({ 'stuid':'201200131012', 'pwd':'23342321' })

loginUrl = '略'

result = opener.open(loginUrl,postdata)

cookie.save(ignore_discard=True, ignore_expires=True)

gradeUrl = '略'

result = opener.open(gradeUrl) print result.read()

当我要切换另一个帐号时，请问如何清除这个全局的 cookie ？