I have done something wrong.?

I had installed AutoCad 2008 on my C drive. Then I moved the main folder to another drive. So it stopped recognizing the autocad files. So I deleted the software. Then I knew that I should have uninstalled it. So I went to control panel and it wasn’t there. Now I’m trying to install it again and it says that auto cad 2008 is already installed. How and where this file is which shows it installed ? Please help.