windows 7 - How am I logged on as a user, when the user doesn't exist in "user accounts"

I logged onto a Windows 7 machine with the username MDC. When I do a "whoami" command it says cityfire\mdc, which I assume means on user "mcd", on "cityfire" domain. But if I look in "user accounts" there is no username "mdc". I assumed it's because I'm logging on to a domain and the "mdc" profile is stored there, but I had no network connectivity at the time i logged in, so it seems the profile is in the local machine itself. So where is is the profile for this user and domain stored on the local machine. There is a folder in Users, but I assume there somewhere else I could look at and edit the user profile? Thanks