I try for 2 weeks to delete some old content that at this time doesn't exist on the site, or in the sitemap so 400 code. The wembaster tools says yes your files doesn't exist, but if I want to remove them from search give me a denied.
In my experience, just being patient will take care of the problem. If the page is gone, and not listed in your sitemap, it will eventually disappear from the webmaster tools.
are those pages supplemental results? google rejects to delete supplemental results using 301 redirect is not solution for supplemental results