Q. How do I clean Registry in Windows 10?

Answer.

Registry cleaning programs are *all* snake oil. Cleaning of the registry isn’t needed and is dangerous. Leave the registry alone and don’t use any registry cleaner. Despite what many people think, and what vendors of registry cleaning software try to convince you of, having unused registry entries doesn’t really hurt you.

The risk of a serious problem caused by a registry cleaner erroneously removing an entry you need is far greater than any potential benefit it may have.

https://support.microsoft.com/en-us/kb/2563254 You also might want to read the section on the CCleaner Registry Cleaner here:

Let me point out that neither I nor anyone else who warns against the use of registry cleaners has ever said that they always cause problems. If they always caused problems, they would disappear from the market almost immediately. Many people have used a registry cleaner and never had a problem with it.

Rather, the problem with a registry cleaner is that it carries with it the substantial *risk* of having a problem. And since there is no benefit to using a registry cleaner, running that risk is a very bad bargain.