Question about CCleaner's reg cleaner

Hi out of curiosity is it safe to delete everything that shows up (after making backup) or only things which I recognize?

What is the worst that could happen?

At the moment I only delete entries which relate to a program I put on myself, if it looks windows related I just leave it.

It should be pretty safe. I never experienced any problem.

And if you would get problem, you can just restore it to prior by running the .reg file which you backed up.

I always let it delete everything it finds.

Would cleanup delete all that is shown? What if I don't want things deleted

Each item can be disselected if you don't want to delete them.