If you wish to limit access to a web site from a given location, perhaps the office, this is known as whitelisting. Within the Web Site node for the site, set the IP Restrictions for this site.
This is useful perhaps to secure the testing site from prying eyes, adding additional security to the web site but restricting access from say the office location (see VPN below), or perhaps putting the Rulevolution developed site behind a proxy server that takes care of SSL certification / logging etc.
This is an advanced topic, therefore if you are having problems please raise a Support Request.
Note:
You should be careful that any IP addresses are static address (like most business connections), and not dynamic addresses (like most residential connections). If your connection is dynamic then when your router or other connection hardware is rebooted, your IP address is likely to change, thus blocking access to your system. Generally remote workers will VPN (use a Virtual Private Network connection) into a central office, in this case the office IP address will appear to be the apparent accessing address.