Funny sequence of posts.
toppergraph replies to WightWalker: no one knows all the mystery's ... unless you Wright your own ...
to wit mystere replies to WightWalker: First, the obligatory Beg The Question // Get it right.
Now that I've annoyed everyone with my pedantics,....
Speaking of my own pedanticism and annoying people with the practice:
Now that I've had a wee bit 'o fun - back to the question that was raised
C:\windows.old is the way we humans see the filename. But I/O doesn't work in human terms.
I guess the answer is the last sentence in the quoted paragraph below.
There are at least two ways that I know of to 'correctly' remove windows.old if it is present
a) Post# 5 points to Disk Cleanup
Windows.old Folder - Delete in Windows 10
b) The free version of Piriform cCleaner also offers to cleanup the folder
I prefer to use native Windows features whenever feasible.