http://www.jv16.org/

on this site you find RegCleaner. I downloaded it, tried it out and found it very reliable, understandable, and the opposite of frightening.

You can for example specify "Corel" and it finds all the references (in more than one time) to "Corel" and you have the opportunity to delete them.

If you don't work against time, time often works for you.