You can just use KUser to remove that user. Click the K button and KUser is in the System directory. I doubt any of those errors are anything to worry about.

You're right about not being able to install from Konsole. Also, knoppix-installer is newer and allows you to choose what to call your user and such. There's not really that much difference between the two scripts. But if you re-install sometime, you might try that one.