maintaining version 2 after upgrade

Hi,
I’ve upgraded to version 3, but maintained version 2 so I can still show previous newsletters on my site.

Today I got several subscriptions for version 2, obviously spam. I have no idea how they managed to subscribe, because there is no form for version 2.0 on my site anymore, but the real problem is that I don’t seem to be able to delete any subscribers or change their subscription to “not in any list”: these functions just don’t work any more.
(in the meantime, I deleted the old forms altogether, so maybe that will help to stop these spam subscriptions.)

My main question is: is there a way to just maintain the earlier newsletters and disable all other functions in version 2?
If that’s not possible, what can I do to delete or alter subscriptions?