Some users have recently been having difficultly removing verified users in Google Webmaster Tools. Google allows you to give multiple users access to view your Google Webmaster Tools reports and data.
Sometimes you want to revoke access to some of those users. To do that, you go "Add or remove owners" on the Webmaster Tools homepage and click "unverify."
But that was not working for the past couple days. Google admitted the bug and said it was fixed last night in a Google Webmaster Help thread. Dennis G. from Google said:
We had a bug in our server that blocked follow-up "unverify" requests, so it was impossible to remove that "Unverification pending" warning. It should be fixed now, so just click that "unverify" link one last time. Sorry for the inconvenience.
Forum discussion at Google Webmaster Help.