Google also has a help page related to the link in the last post, on which it advises:

When NOT to use the URL removal tool

The URL removal tool is intended for pages that urgently need to be removed—for example, if they contain confidential data that was accidentally exposed. Using the tool for other purposes may cause problems for your site.

Don’t use the URL tool to get rid of pages in these circumstances:

To clean up cruft, like old pages that 404. If you recently changed your site and now have some outdated URLs in the index, Google's crawlers will see this as we recrawl your URLs, and those pages will naturally drop out of our search results.
There's no need to request an urgent removal.

To remove crawl errors from your Webmaster Tools account. The removal tool removes URLs from Google's search results, not from your Webmaster Tools account. You don’t need to manually remove URLs from this report; they will drop out naturally over time.