Laptop: back to factory settings and delete everything?

My laptop has slowed down lately and I wanted to delete everything.

The most important files I've already pulled down. But what exactly and where do I have to go to not delete everything. Windows etc. Should not go away.

In the settings under Update and Security you can reset your computer.

Slowly the computer is not because a lot of data on it but because the Systemdatein are garbage like Registry. It then has tens of thousands of entries in thousands of sub-subdirectories.

To get back to speed either Windows down and reinstalled again or the garbage in the important places to be removed.

This is so halfway with cleaning programs as CCleaner.

With Ccleaner or Cleanmaster is cleaned vigorously and I have become accustomed to go through this action even at the end even Defragler 2x. I only recommend Ccleaner and Defragler to download from Piriform; With third-party providers, it can happen that you still get unwanted additional software installed. Windows and other proprietary software will not be destroyed.

Another step would be to correct the "startup" table in Ccleaner or in Windows, too, so that rarely used programs are "not" started automatically with Windows and run continuously in the background. As a result, the programs are not deleted from the disk and still running at the selection.

Oh yes: The two cleaning programs are free in the simple version.