The student needs to submit the quiz. (You could do it for them using https://docs.moodle.org/en/Log_in_as, if you have permission to do that.)
If the quiz has I time limit, then you could look at the 'When time expires' quiz setting.
And, you could vote for this feature request: MDL-24814.
If the quiz has I time limit, then you could look at the 'When time expires' quiz setting.
And, you could vote for this feature request: MDL-24814.