Not sure if this is available in MCE, but this is, by far, the tidiest way to fix this: Open the User Accounts control panel. Create a new account for her with the correct name, making sure she's in the same group as the existing account (probably Administrators), log in with that account, delete the old account, then delete the offending directories.

If MCE doesn't have the User Accounts control panel, then you'll likely have to do some regedit goodness. Google for "Documents-and-Settings regedit". TweakUI ought to do it, but it doesn't actually seem to.