How to remove an old company account from Authenticator App

Question

I have worked for a company and we have used everything Microsoft does provide and the IT management create an Microsoft account for me for work purposes and because we had to have two steps authentication I decided to use my authentication app from Microsoft that I already use for private purposes. It worked all fine but now I don't work for the company anymore, my work account has been deleted but I cannot delete it from my authenticator app because it is all grey and I just can't do anything with it, did someone have the same problem and how do you solve it