Permanently delete your entire OneDrive | Microsoft Support

Select any shared folders and choose Remove shortcut. If you are completely sure you want to purge your entire OneDrive, open the OneDrive Recycle bin and select Empty Recycle bin. Select Yes to confirm. Tip It might be a good idea to wait a short time after deleting your OneDrive files before emptying your OneDrive recycle bin - just to make sure.

Source: support.microsoft.com