A Microsoft file hosting and synchronization service.
Hello
Are you having trouble signing back into the computer or signing into OneDrive? Please clarify.
If it is Windows, I think your uncle must be using the computer with his work account in the past. Is there anyway you can still get in touch with your uncle and find out if he remembers setting up a local user on that specific device prior?
Alternatively, it is probably best that you clean install this computer to start over, so the computer can be truly set up as yours for personal use, instead of inheriting any organization settings and policies from your uncle's old settings. I am happy to give you that instructions, but I do want you to clarify that it is indeed Windows you cannot get into first.