How do I delete a Microsoft account

My Windows Phone tells me in the "email + accounts" section of "Settings" that I have two Microsoft accounts. One account is named "Microsoft Account" and has a username that contains the domain name for an old, no longer active, email account; I think this service used to be called Microsoft Live or Live.com. The other account is named "Outlook" and contains the domain name of my current active email account. I think I want to delete the no-longer-active account. I cannot find it at all when I go to www.outlook.com. I cannot figure out how to delete it from my phone. Any suggestions would be appreciated.