Can you elaborate a bit more on what you means by "modify"? Do you want to just remove programs? For many things, it's as easy as deleting the application. A Spotlight search often turns a couple of small preference files that can be deleted, but it's not important to remove them. Apple apps are often a bit more complex to remove as they sometimes have large libraries of support files buried in places like "Application Support" in one of your Library folders. What else do you want to do?