I installed Windows 10 on this computer from the scratch and downloaded & installed Windows 10 Fall Creator Update.
When I check the root directory of C drive, I see not only C:\Windows folder, but also C:\Windows.old folder which is about 30GB.
Anyway is it ok to erase this folder thru Disk Cleanup/Clean up system files and check "Previous Windows installation ... 30GB" provided I won't go back to prior to Fall creator update time?
I assume that it was Windows Fall Creator update that had to create Windows.old folder?
I thought that Windows.old folder is usually created when upgrading Win7/Win8 to Win10 and it is for the case if the user wants to go back to the previous OS.