You don't need the supplied disk to do that. Just connect to router config page and goto security settings. You will find the settings available there. Make the disired changes there and save settings. Router will most likely reboot and you should be fine.
If you dont know the IP of the router, check your PCs IP settings, it should be the address displayed in the "Gateway" field. Type it into your browser and press enter. You will be asked for a password, once entered you will have access to make changes.