Which two plugins created the problem?
I've seen pages that no longer exist linger in Google for up to four years, even when they are generating a valid status code 404. The problem is that Google has to check the page before it will see the robots tag or does anything about it. If GoogleBot no longer finds links with that URL, it can take some time. I hope yours get cleared out sooner than four years.
Keep up updated.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen