Run Disk Cleanup and Ccleaner, including Tools > System Restore to remove old Restore Points. Search Create a Restore Point to make a fresh one
This will give you a little bit of space
For W10 Home and W10 Pro, I have neither C:\ProgramData\Windows directory nor "windows.sys" and Google doesn't mention it. Possibly it's app or malware related
Rename it to windows.syk, say, and see if you can boot and use Windows normally
If you can't, boot to Advanced Boot Menu > Command Prompt and type
rename windows.syk windows.sys to put it back again.
Scan with Malwarebytes Free as a precaution
When happy it is not needed, delete it.