I am not sure why this issue is happening. It does look like you have a repository from Learning Lab already on your account, but I can't see it. That means you either deleted it, or it's private.
I can delete your user account from Learning Lab, which would have you re-register. This shouldn't delete your repositories if you still have them, but it will un-register you from the courses you've started. Is this OK?
Yes, thank you for your patience @RoelofWobben. I've been unable to delete your account, but I've contacted an engineer on our team who will have it sorted out shortly. I'll be sure to update here once I know more.