Direct link to delete your complete Google account, including ALL services (be aware!). See also http://www.google.com/support/accounts/bin/answer.py?answer=32046
If you're from the EU, and want to remove yourself from Google's search results, you can use the 'Right to be forgotten' form found here: https://support.google.com/legal/contact/lr_eudpa?product=websearch - success is by no means guaranteed while your request will be judged on various legal criteria. See the link for more information.
If you can't find any contact info and still wish to ask something, for example a question about what exactly is deleted, about data retention, etc., you may contact the domain owners using this info.