I apologize for the difficulty with the CAPTCHA, it seems to happen inconsistently for some users and we haven't narrowed down a cause or solution. I'm glad you were able to find a work around.
I'm not sure how it would leave that behind, but that is stored in your Configuration/Menus/menus.xml file, so it could be removed manually. You could also try re-installing and uninstalling again, which should also remove those links.
If you upload a copy of your Configuration/Menus/menus.xml file I can update it and send you the file with those lines removed.