特定の日時で投票を自動的に終了させる方法はありますか？
No, but it has been requested a lot and I would like to add it.
「いいね！」 10
It’s been on my 
since the inception of polls.
Consider it bumped 
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The nice thing is that now we have the generalised system @tgxworld extracted, so it should be far simpler to build… waiting pays off sometimes! 
「いいね！」 6
「いいね！」 9
And here a live example 
- Discourse
- Rocks
0
voters
「いいね！」 11
@zogstrip, is it intentional that auto-closed polls cannot be reopened? Polls without a timer can be opened and closed as needed by staff.
It is indeed intentional. If there’s a close date, and it has passed, then it’s closed.
「いいね！」 2