Are you aware of the consequences? It means that your Google ranking can drop sharply and to the point where your website is kicked out of the index for manipulation tactics. Generally speaking: When you hide something from Google that normal users can see, your website will be punished by Google.
If you want to do that, you could block Google from reading parts of your site by adding some .htaccess rules that treat Google like it was a bad bot. For example create an .htaccess file in the directory that Google shall not be able to read and put this into it:
Code:
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_USER_AGENT} ([Gg]ooglebot) [NC]
RewriteRule .* - [F]
It will keep all requests out that use "googlebot" as the bot name in the current directory (where the .htaccess file is located) and all descending directories. However, when Google shows up with an anonymous ip, it will still be able to read the directory content, and you will not be able to keep them from checking with IPs that you don't know. The better solution is definitely to let them spider the site and tell them through a robots.txt what pages and directories you don't want them to include in their index.