How can I change the url for a users blogger page?

I have a user that started using our system with his email as his login and I believe that is why his blogger url for the link about Additional blogs by the user have his email address in them. He has since started using his own login but I have not figured out how to remove his email reference from his url which is currently:

https://www.drcarney.com/blog/bloggers/blogger/kenscircus-aol-com

But we would like it to change to

https://www.drcarney.com/blog/bloggers/blogger/kenscircus

Any pointers would be appreciated.

Thanks,