How to remove blocked university account?

For the past 4 years I had my university Microsoft account. Now that I finished studying, it was blocked and I can't access it, but it still exists in Windows and I keep getting notifications from Windows that there is a problem with my Microsoft account (because it does not exist anymore...)

This user shows up under Settings > Email & accounts > Add a work or school account

I click on Manage, but it opens up a browser to log into the account, but I can't of course, with the message:
Your account is currently blocked from signing in. As a result, you may not reset your password at this time. Please contact an admin in your organisation and ask him or her to unblock your account.

What can I do?

Thanks