There are several options to prevent your web site from being indexed by Google. For best results it is highly recommended to use all of them. Otherwise your web site might still appear in search results.
The first is using a robots.txt file. Basically what you need to do is create a file named robots.txt with the following content:
User-agent: *
Disallow: /
Then place this file in the web root for your domain name. Such robots.txt file should prevent all web crawlers from indexing your web site. Note however, that in this case Google will still index your pages that are linked from other web sites.
The second option is to set a "noindex" meta tag for your pages. If the meta tag you have for the page is "noindex", Google will completely drop the page from the search results. If the page/website is currently indexed, it should be removed the next time it is crawled by Google.
The third option is to use Google Webmaster Tools. Here are step-by-step instructions how to use them:
1. You will need to create an account with Google Webmaster Tools.
2. Log in to your Google Webmaster Tools account.
3. If the account is new, you will have to add your web site.
1. Click the "Add a site" button.
2. Enter your web site URL and click "Continue"
4. Now you need to access the web site removal tool.
5. Once you have opened the web site removal tool, click on "New Removal Request".
6. On the 'Create a new request' page, select the options that match your removal request, fill in the required fields and then click the Submit Request button
