These instructions are for Ubuntu 12.04 running the Unity desktop on which the Kubuntu Desktop was installed using either the Ubuntu Software Center or sudo apt-get on the command line.

The instructions may be the same for other versions of Ubuntu, but no guarantee is made.

When the Kubuntu Desktop is installed in Ubuntu 12.04, it installs several packages and libraries it requires as well as some optional packages. Not all these packages and libraries are uninstalled when you uninstall Kubuntu Desktop. Several packages (like dolphin and kmail) do not get uninstalled.

Quick Uninstall

This is not recommended because it will remove all packages normally installed with Kubuntu Desktop. This may include packages you previously installed (like dolphin or kmail) or packages that were installed when you installed some other program.

Note: this uninstall command assumes Kubuntu Desktop was installed on a fresh Ubuntu 12.04.

1) Open a terminal (instructions can be found here).

2) Enter the following command (it is very long and a single line):

sudo apt-get purge --auto-remove akonadi-backend-mysql akonadi-server akregator amarok amarok-common amarok-utils  apport-kde apturl-kde ark bluedevil cdparanoia cdrdao cryptsetup docbook-xsl  dolphin dragonplayer freespacenotifier gnupg-agent gnupg2 gpgsm gpsd  gstreamer0.10-qapt gtk2-engines-oxygen gtk3-engines-oxygen gwenview ibus-qt4  icoutils jockey-kde k3b k3b-data kaccessible kaddressbook kamera kate kate-data  katepart kcalc kde-baseapps-bin kde-baseapps-data kde-config-gtk  kde-config-touchpad kde-runtime kde-runtime-data kde-style-oxygen  kde-wallpapers-default kde-window-manager kde-window-manager-common  kde-workspace kde-workspace-bin kde-workspace-data kde-workspace-kgreet-plugins  kde-zeroconf kdegames-card-data kdegraphics-strigi-analyzer kdelibs-bin  kdelibs5-data kdelibs5-plugins kdemultimedia-kio-plugins kdenetwork-filesharing  kdepasswd kdepim-kresources kdepim-runtime kdepim-strigi-plugins  kdepimlibs-kio-plugins kdesudo kdm kdoctools khelpcenter4 kinfocenter klipper  kmag kmail kmenuedit kmix kmousetool knotes konsole kontact kopete  kopete-message-indicator korganizer kpat kppp ksnapshot ksysguard ksysguardd  ksystemlog ktimetracker ktorrent ktorrent-data kubuntu-debug-installer  kubuntu-default-settings kubuntu-desktop kubuntu-firefox-installer  kubuntu-netbook-default-settings kubuntu-notification-helper  kubuntu-web-shortcuts kvkbd kwalletmanager language-selector-kde  libakonadi-calendar4 libakonadi-contact4 libakonadi-kabc4 libakonadi-kcal4  libakonadi-kde4 libakonadi-kmime4 libakonadi-notes4 libakonadiprotocolinternals1  libassuan0 libattica0.3 libbluedevil1 libboost-program-options1.46.1  libcalendarsupport4 libcln6 libclucene0ldbl libdebconf-kde0 libdlrestrictions1  libdmtx0a libencode-locale-perl libepub0 libeventviews4 libfile-listing-perl  libflac++6 libfont-afm-perl libgadu3 libgpgme++2 libgps20 libgrantlee-core0  libhtml-form-perl libhtml-format-perl libhtml-parser-perl libhtml-tagset-perl  libhtml-tree-perl libhttp-cookies-perl libhttp-daemon-perl libhttp-date-perl  libhttp-message-perl libhttp-negotiate-perl libibus-qt1 libilmbase6  libincidenceeditorsng4 libindicate-qt1 libio-socket-inet6-perl  libio-socket-ssl-perl libk3b6 libkabc4 libkactivities-bin libkactivities6  libkalarmcal2 libkateinterfaces4 libkatepartinterfaces4 libkblog4 libkcal4  libkcalcore4 libkcalutils4 libkcddb4 libkcmutils4 libkde3support4  libkdeclarative5 libkdecorations4 libkdecore5 libkdegames5a libkdepim4  libkdepimdbusinterfaces4 libkdesu5 libkdeui5 libkdewebkit5 libkdgantt2  libkdnssd4 libkemoticons4 libkephal4abi1 libkexiv2-10 libkexiv2-data libkfile4  libkholidays4 libkhtml5 libkidletime4 libkimap4 libkio5 libkipi-data libkipi8  libkjsapi4 libkjsembed4 libkldap4 libkleo4 libkmanagesieve4 libkmbox4  libkmediaplayer4 libkmime4 libknewstuff2-4 libknewstuff3-4 libknotifyconfig4  libkntlm4 libkonq-common libkonq5-templates libkonq5abi1 libkontactinterface4  libkopete4 libkparts4 libkpgp4 libkpimidentities4 libkpimtextedit4 libkpimutils4  libkprintutils4 libkpty4 libkresources4 libkrosscore4 libksba8 libkscreensaver5  libksgrd4 libksieve4 libksieveui4 libksignalplotter4 libktexteditor4 libktnef4  libktorrent-l10n libktorrent3 libkunitconversion4 libkwineffects1abi3  libkwinglutils1 libkwinnvidiahack4 libkworkspace4abi1 libkxmlrpcclient4  liblastfm0 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocol-https-perl  libmailcommon4 libmailtools-perl libmailtransport4 libmessagecomposer4  libmessagecore4 libmessagelist4 libmessageviewer4 libmicroblog4 libmsn0.3  libmuonprivate1 libmygpo-qt1 libnepomuk4 libnepomukdatamanagement4  libnepomukquery4a libnepomuksync4 libnepomukutils4 libnet-http-perl  libnet-ssleay-perl libntrack-qt4-1 libntrack0 libokularcore1abi1 libopenexr6  libotr2 libphonon4 libplasma-geolocation-interface4 libplasma3  libplasmaclock4abi3 libplasmagenericshell4 libpolkit-qt-1-1 libpoppler-qt4-3  libprison0 libprocesscore4abi1 libprocessui4a libqalculate5 libqapt-runtime  libqapt1 libqca2 libqca2-plugin-ossl libqgpgme1 libqimageblitz4 libqjson0  libqrencode3 libqt4-qt3support libqtglib-2.0-0 libqtgstreamer-0.10-0  libqtscript4-core libqtscript4-gui libqtscript4-network libqtscript4-sql  libqtscript4-uitools libqtscript4-xml libreoffice-kde libreoffice-style-oxygen  libsocket6-perl libsolid4 libsolidcontrol4abi2 libsolidcontrolifaces4abi2  libsoprano4 libstreamanalyzer0 libstreams0 libsyndication4 libtag-extras1  libtaskmanager4abi3 libtemplateparser4 libthreadweaver4 libtimedate-perl  liburi-perl libvirtodbc0 libweather-ion6 libwww-perl libwww-robotrules-perl  libxml2-utils libxss1 libzip2 muon muon-installer muon-notifier muon-updater  mysql-client-core-5.5 mysql-server-core-5.5 ntrack-module-libnl-0 odbcinst  odbcinst1debian2 okular okular-extra-backends oxygen-cursor-theme  oxygen-icon-theme partitionmanager phonon phonon-backend-gstreamer pinentry-gtk2  pinentry-qt4 plasma-dataengines-addons plasma-dataengines-workspace  plasma-desktop plasma-netbook plasma-scriptengine-javascript  plasma-scriptengine-python plasma-widget-facebook plasma-widget-folderview  plasma-widget-kimpanel plasma-widget-menubar plasma-widget-message-indicator  plasma-widget-networkmanagement plasma-widgets-addons plasma-widgets-workspace  plymouth-theme-kubuntu-logo plymouth-theme-kubuntu-text polkit-kde-1  printer-applet python-kde4 python-pyudev qapt-batch qapt-deb-installer quassel  quassel-data rekonq shared-desktop-ontologies software-properties-kde  soprano-daemon system-config-printer-kde systemsettings tasks-icons  update-manager-kde usb-creator-kde userconfig virtuoso-minimal  virtuoso-opensource-6.1-bin virtuoso-opensource-6.1-common xsettings-kde

It is easiest to copy the line and paste it into the terminal (right-click on the terminal and select Paste from the popup menu).

Preferred Uninstall

The better way to uninstall it is to follow the directions on this page.

This will show you on how to uninstall only the packages that were installed when Kubuntu Desktop was installed. The instructions are generic and work for any installed package.

It involves:

identifying which packages were installed and
creating a command to uninstall only those packages

It leaves intact any packages you may have installed (like dolphin or kmail) or were installed previously as part of other packages instead of blindly assuming that they were installed along with Kubuntu Desktop.