You're going to have to make your own mind up with this because wherever you ask this question, either here in these forums or elsewhere, you are going to get polarised views and advice.
Here's my polarised view and advice;
The Windows Registry is just a database and it is not particularly large at that. It just has text or numeric entries. Databases are useful for holding data, (information), as and when that data is required. If a database entry is never used, it just sits there doing nothing. It doesn't clog up the database, It doesn't slow down access to any other part of the database. It just sits there doing nothing.
That's all the Windows registry is. Any unused entries in it are ignored. It makes no difference to the performance of the OS. It doesn't need defragging and it doesn't need cleaning. Unnecessary entries do not need to be removed.
While there may have been a case for doing that in Windows 95/98, (I never had trouble), the registry in later Windows versions has become much more stable ad much better able to look after itself.
I see no reason to touch the registry.