The November update for Windows 10 is huge and it requires a lot of disk space to download. In fact, it requires over 4GB of disk space.
When the update installs, it renames the old C:\Windows folder to C:\Windows and installs a fresh copy of the operating system. It keeps all your personal files, so nothing is lost, but it does change a few settings.
File associations are changed for example, and if you have set up Firefox or Chrome as the default browser, then it switches back to Edge. This isn’t Microsoft forcing Edge on everyone and other settings are reset too. I prefer Windows Photo Viewer for viewing images to the Photos app and had changed the association, but the update changed it back.
Open Explorer and select This PC on the left. Open the C: drive and you will see that there is a C:\Windows folder and C:\Windows.old. Right click Windows.old and select Properties on the menu that is displayed. Give it a minute or two and it will display the size. It looks something like this
The previous version of Windows is saved in this folder and if the new updated version is not working properly, it can be uninstalled. Go to Start, Settings and click Update & security. Select Recovery on the left and on the right is Go back to an earlier build. Click Get started to restore the old version of Windows 10 if you really don't want the current version.
This was the case with the original Windows 10 upgrade and after a month or so, the Windows.old folder was automatically deleted. If you don’t want to wait and you really need the disk space, the folder and the installation files can be removed.
Go to the Start menu and click All apps. Scroll down to the bottom and expand Windows Administrative tools. Click Disk Clean-up. This tool finds junk and unnecessary files on the disk drive and lets you select it and delete it.
Let it scan the disk drive and when it has finished, click the button, Clean up system files. This makes it scan the disk again, but this time it performs a more thorough job and it finds even more junk.
Just look at the total number of junk files that can be cleaned when everything is ticked – a massive 40GB! To be fair, I do have 11.8GB of files in the Recycle Bin, but that still leaves about 28GB of junk. The previous Windows installation is 22.5GB all on its own.
If you have plenty of free disk space then I would recommend keeping the previous Windows installation, but if you are really short of space then let Disk Clean-up remove it.