If you are talking about the core server, and not just the console or an agent that is different.
If you are talking core server, your best bet is to re-image the machine to do a clean install. You will spend far more time trying to clean up a core install than you would installing a fresh OS and probably still will never be successful getting everything removed from all the areas the core touches.
IIS in particular is near impossible.
I had to use a tool to search the registry for "landesk" and deleted everything related to it ... then it worked.
Thank you very much for the answers.