Remove authorization on a computer

I was previously a student at the University of Michigan and authorized digital editions on my computer with my old univeristy email address so I could acess library materials back in 2013-2014. 

I now am at a different university and can't download an ebook because that authorization doesn't match my new university credentials. 

I don't remember the password for that account and don't know how to recover it as I don't have access to that email address anymore. Becuase of this I am not able to remove that authorization. Support says they replaced the email address on my account to match my new credentials and I reset the password, but that password doesn't work. 

Is there any way to fix this, or can I just not use this device for materials from this particular database anymore?