I tried to manually enroll a user. I received an error. The user was not displayed in the list of participants.
I logged out of Moodle and later logged back in to the application.
I tried to enroll the user again and recieved an error indicating a duplicate user.
I changed the username and password and received an error for duplicate email address.
Since the user isn't in the system I cannot delete this user, but I don't know how to get rid of the user information that was stored somewhere during the original attempt at enrollment.