I reinstalled windows 10 pro this May too, but it placed the documents folder on the system drive inside my user folder...
If you can find the documents folder on your oneDrive, right click it and select properties.
There should be a tab in the properties window called "location", there you can change where your users documents folder is located.
I've done this to get those files off my 500 GB SSD system drive over to a 3 TB HDD.
My documents folder is 5 GB in size and almost every program writes to files there now and again. I like to spare my SSD from those extra writes when I can to increase its lifetime.
Never heard about windows putting those files in OneDrive, so I don't know if it can be moved away from there the same way one usually moves its location.