I've asked multiple people when this question came up in the past, and we just don't know. The ED PLUS is still rather new, and this situation has not been talked about much. Traditionally, you would get a letter from your school that states when you finished studying, and use that to cancel your extension. But with ED plus, you ALREADY finished cancelling. Most schools will not provide any additional documentation because there's nothing to provide. You finished studying a while ago, there's nothing for them to report. You can TRY asking immigration if they want/require you to cancel your ED plus extension, but so far I've not seen anyone talk about if they ended up doing this or not. Normally the way a "grace" period works is that your documentation from the school has a date, and you can go in 1-2 weeks before that date to do the cancellation, and they will stamp you back in until the date on the letter. Otherwise the cancellation is effective the date you attend immigration, there is no 7 days to leave.
