RegCleaner deletes registry entries. You can delete DLLs with the Shared DLLs feature, and shortcut files with the Startup feature. You don't even have to know what the registry actually is to be able to use RegCleaner.

You can use RegCleaner because it's a good idea to keep the registry as clean as possible. Here are some examples to help you understand how RegCleaner can truly help you:

Say you've accidentally destroyed a nice shareware program that has a 30-day trial period. Later on, when you notice that it's been destroyed, you try reinstalling it, only to find out that you can't, because the program thinks that you're just trying to get another 30 days.

If you first remove the program's registry entries, however, you may very well be able to reinstall the software and recover your trial period again.

You've found that your favorite program is an older version, and you want to download the latest whiz-bang version. The program, however, doesn't provide any uninstall utility, so you simply destroy its files and cross your fingers. But, as fate would have it, when you try to install the latest version, you see a dialog box such as this:
"Please uninstall the old version of this program before attempting to run this installation."