Newbie here. I have been pulling my hair out over One Drive issues with my Library file. I uninstalled One Drive but the Arduino IDE kept insisting on the path to the now deleted One Drive user documents folder. Even though my explorer showed it as "Documents" the IDE insisted on looking for "OneDrive\Documents. I could not include any library files. After spending hours looking for a solution, registry searches, arduino preferences etc, I by chance right clicked the Documents folder, went to Properties and under the locations tab I chose "Restore Default" .....bingo, problem solved. I post this because in researching the issue I found scores of others suffering this MS induced insanity. Hope this helps someone.
Yeah, I don't trust OneDrive. I immediately disabled as much of that sort of thing as possible immediately after I installed Windows 10.
You should be able to set the Arduino IDE to use any folder on your computer as the sketchbook via the File > Preferences > Sketchbook location setting. It just defaults to the Documents folder.