OK this is driving me crazy

FSX demo 2 will not leave my hardrive. No matter what I do it just wants to repair its self never uninstalls its self.I have tried to remove the registry entries for it. I have used a tool that deletes it from the add and remove list. I have ran a registry cleaner and it keeps comming back like a virus almost. Anybody else have the demo haunting their computer.:-walksmile