A few years ago my ex got a new laptop and it had onedrive enabled system-wide by default. She didn't realize until after she had been using it for months, I had to spend several hours backing up her files and defenestrating onedrive. It not as simple as just turning it off because it was even on critical system folders, you have to go in the registry and remap the those folders manually one at time before you can disable it.

It is possible, but it fucking sucks.