How to fix AADSTS50020 " Sign out and sign in again with a different Azure Active Directory user account."

Question

My problem is that I had an Microsoft 365 account with University of Glasgow - now all my apps on my Macbook are connected to that account. The account was deactivated (I am no longer a student there) and deleted, however when I try to log in my other account that has a licence - it doesn't give me an option to do so - only in the tenant of University of Glasgow domain.

I can't Sign out and sign in again with a different Azure Active Directory user account, because my email for University of Glasgow is deactivated, so it no longer works.

Please help.