If you would like to redirect all the requests to the www version of an URL to the non-www version - for example http://www.geekpedia.com to http://geekpedia.com - you can do that by placing the following mod_rewrite rule in your .htaccess file:

RewriteCond %{HTTP_HOST} ^www\.geekpedia\.com$ [NC]
RewriteRule ^(.*)$ http://geekpedia.com/$1 [R=301,L]

The redirect code 301 means Moved Permanently so most search engines will pick this up and send visitors directly to the non-www version of your URL.