Email shown under Auth tab

Question

When opening the Microsoft Authenticator, in the Auth tab on the opening screen there is my account with an arrow, and under it is my work email. I never authorized my work email and I'm not sure how it made it onto the opening page in Authenticator. It is greyed out so I can't click it, and I don't see the email anywhere else. My password had been stolen at work and now thousands of attempts are being made on my Microsoft account. I did have that email in my Outlook, but I removed it and would like to competely remove it. What is the opening tab of the Authenticator app? There is no discription, no options and no explanation as to what the tab is even for. It just lists my main account up top with an option to remove it. The account under it I want to remove buy it's grey.