Update your config.php for the url you want.
And if you have access to your apache virtualhost config
<VirtualHost *:80>
ServerAdmin postmaster@example.org
DocumentRoot /home/example.org/htdocs/www
ServerName www.example.org
<Directory /home/example.org/htdocs/www>
Options Indexes FollowSymLinks
AllowOverride All
Order allow,deny
Allow from all
</Directory>
CustomLog ${APACHE_LOG_DIR}/example.org-access.log common
ErrorLog ${APACHE_LOG_DIR}/example.org-error.log
</VirtualHost>
<VirtualHost *:80>
ServerAdmin postmaster@example.org
DocumentRoot /home/example.org/htdocs/www
ServerName example.org
redirect permanent / http://www.example.org/
</VirtualHost>
Change the document root according .
