Redirect non-www to www URL's using htaccess and Vice Versa

# Redirect non-www to www:
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

www to non-www

# Redirect www to non-www
RewriteCond %{HTTP_HOST} ^www\.(.*) [NC]
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

Or try this link

http://www.thesitewizard.com/apache/redirect-domain-www-subdomain.shtml