I have a used Iphone 4S with a passcode that was forgotten and the original computer is no longer in service, what can I do.

The only thing to do is to follow the information on the support document that you linked from that talks about not syncing with a computer. Read further down. You will have to restore the phone as new. Also, make sure you have the Apple ID and password for the original owner that activated the phone, unless they have already deactivated Find My iPhone.

You must restore it as New following the instructions in the tech note you were reading when you posted your message.