ScenarioHistory: several years ago, before Panda and Penguin, you made a blog and posted some “made-for-Google” content there, with the only purpose of getting links to your main site.
Our days: you've learned that your spammy blog will cause a penalty, sooner or later, and decided to get rid of it.
Proposed (and failed) ActionGoogle says (here):
If you wish to remove your content using the URL removal request tool in our Google Webmaster Tools ...
To remove a directory and its contents, or your whole site, you must ensure that the pages you want to remove have been blocked using a robots.txt file.
Indeed, in a very short time, you try the site:my-crappy-blog.com query, and there is no results. Voila, it worked!
But then, you click on the “Links To Your Site” in the Webmaster Tools, and still see all the links, from the site that you have removed!
Just takes time?
... forever. Links are there.
Content removed with this tool will be excluded from the Google index for a minimum of 90 days.... and then what? So, the removal was only temporary?
Google clarifies (here):
Content removed using the URL removal tool will not appear in search results for a minimum of 90 days or until the content has been removed from the Google index. However, if you've updated robots.txt, added meta tags, or password-protected content to prevent it being crawled, the content should naturally have dropped out of our index, and you shouldn't need to worry about it reappearing after 90 days.What about the links?
Nobody said anything about links! I've been watching the links from a removed site for about 6 months, in the Webmaster Tools.
The cureDo not remove the site using Webmaster Tools; do not place robots.txt or meta tags.
Make sure that Googlebot can crawl the entire site. That means, NO robots.txt!
Remove the CONTENT of the site. Let Google see empty pages, maybe with some text like “This site does not exist anymore. Good-bye!”.
Now, relax and watch your links disappear from the Tools.
P.S. The same applies for "glued" sites (when info:site1 and info:site2 show the same information). After cleaning the content, the sites will be "unglued".