Oracle Database Discussions

I am a tester and have to regularly uninstall software and reinstall it. unfortunately Oracle does not seem to be designed to do this. I have used the uninstall facility but this does not put the computer back to how it was before I installed it. I deleted the left over files in Program files and the Oracle folder that holds the ora92 files. I also deleted mention of Oracle path under Local_machine/Software in the Registry. I tried reinstalling but the Net configuration assistant would not reinstall the missing Listener files because it says the Listener is already installed. The software I am trying to use Oracle with cant find the listener because some files it needs are missing. I deleted all Oracle services and tried reconfiguring and renaming the listener to get it to reinstall but no luck. The PC is in a mess. What are the files/settings I need to delete to allow a full reinstall including for listener please?