uninstalling Counter Spy

I had a trojan horse infection and I did all the steps in the in the tutorial on getting rid of malware. It worked and everything is working fine!!! Thank you! Now I am having trouble uninstalling CounterSpy by Sun Belt. When I go to the add and remove programs it is listed but I don't have the option to uninstall, there is only a button to "change". When I click the change button it tries to get me to pay for the product. The trial period has expired and I want it off, as I am using AVG and like it. Could someone tell me why I can not uninstall?
Thanks so much.