Problems installing on 10.6.8

I have the same problem but on Mac running osx 10.6.8. It will neither update nor uninstall, and says installation may not be allowed by administrator. But I am administrator. And I also did a permissions repair on disc. The problem is stopping me from doing a full disc backup using SuperDuper and updating osx to Lion. I read that if you simply delete the Air folder, it still leaves traces on the system and creates later issues with reinstall. So how do I get rid of it?