Remove Microsoft account email from a local account on windows 10?

I have a computer that one of the admin accounts that says it is a local account AND an administrator account for some reason has my son's microsoft family account email attached to it.
I can't seem to find any way to remove it from this computer and even through we have removed this device from my son's list of devices on family safety.  This computer continues to be locked out according to the family safety schedule!

How do I remove that email from the Account on this computer?

This has never been my son's computer, he has never used it.  About all I can figure is I must have once tried to check his email from this computer for him.