Changing Multi-Site from convert subdirectories to subdomains

I have setup my network and been running it for a while.

https://spinabifidaassociation.org/
https://spinabifidaassociation.org/sbaofca/
https://spinabifidaassociation.org/sbnationalconference/home/

I would like to now convert them over to subdirectories

To
https://spinabifidaassociation.org/
https://sbaofca.spinabifidaassociation.org/
https://sbnationalconference.spinabifidaassociation.org/

What is the process to do that with out reinstalling everything?

Thanks everyone for your support and help.

Thanks,
Jay