Eliah Kagan's answer to how to remove KDE here (How to remove all traces of KDE installed) is a great first step in removing KDE from a Ubunutu, but I still have remnants of KDE that were not removed in Plymouth and LightDM. How do you remove these?
The steps in the previous question will remove all of the KDE software, but it won't restore your system back to pre-KDE install state. There are two additional steps that I had to do to restore my system to pre-installation of kubuntu-desktop.
The first was to modify the Plymouth configuration to remove the "Kubuntu" splash screen (this is just cosmetic, but still annoying and unclean, documented here 1):
And the second was to restore the lightdm configruation to use the unity-greeter instead of kde-plasma-greeter. First run this command to open the lightdm configuration page -
and then edit it to replace these lines: