A Microsoft file hosting and synchronization service.
I believe I disable syncing, and then uninstalled OneDrive to get it off my PC. I also then manually deleted all the folders associated with it and used the regular Windows PC folders to store things. The folders are named similarly so I deleted them to confused the two. That said my One Drive folders were mostly empty. I just didn't want all my personal documents/folders to be automatically synced to the cloud so that's why I did that. I never went over the limit where they ask you to pay. I still think I have the 5GB free account but I treat it as another Dropbox account. I'm not sure what you mean by locked, you should be able to access it through https://www.microsoft.com/en-us/microsoft-365/onedrive/online-cloud-storage and use whatever email it asked you during PC setup.