We do have an offline activation process if your computer is permanently offline for CS6. It is much easier though to simply connect your computer to the Internet to activate.
If that is not possible then you can find more details regarding the offline process at Activation, deactivation | Adobe products - http://helpx.adobe.com/x-productkb/policy-pricing/activation-deactivat ion-products.html. It should be noted you will need a device with Internet connection to complete the offline deactivation process, i.e. smartphone, tablet, or another computer.
also just a FYI i had the beta program on that machine and missed the important step of deactivating it before i uninstalled it...but the adobe customer service was very helpful in helping me get the retail version unlocked