remove user profile

A guest using my computer created or modified my existing
logon user profile, on my ME machine (I previously had no
users and no networking password). I would like to remove
all users and tried the approach described in article
156826. Unfortunately, I was unable to locate a
the "ProfileList" in the registry, as stated in the
article.

When I start my machine the new user name is in the logon
name (when before there was none), no password is
required. my outlook email does not work and cookies are
now being created in the name in the logon box. I assume
that I need to delete the user profile, but cannot find
it. I noticed that a new pwl file has been created in the
name of the user.