I need help permanently deleting my previous employer’s Outlook account on my installed Microsoft Office for MAC.

I have Microsoft Office installed on my MAC. When I installed it I was using an employer's email account so it defaults to that when I try to open it from my desktop. I no longer work for that employer. When I try to open Outlook on my desktop I obviously get the error of email invalid but it shows some of my old work emails. I want to permanently delete this account and set it up with my Yahoo email address and be able to use the calendar. I have read other answers that say to go to the control panel but I can't even find that on my desktop. Help!!!!