I was using Ubuntu 15.10 and decided to try KDE. I installed kubuntu-desktop. I did not like it and now want to remove it completely.
But the problem is, running this command
$ sudo apt-get purge kubuntu-desktop
The following packages will be REMOVED:
kubuntu-desktop*
0 upgraded, 0 newly installed, 1 to remove and 7 not upgraded.
After this operation, 41.0 kB disk space will be freed.
which means it still is not removing it completely. How do I remove it completely.
Yes, this command will remove kubuntu-desktop completely. Even if it says 41 kb of data will be removed, a lot of it will actually be removed. But there is a problem: KDE will be removed, but other programs installed with it will not.
I suggest that you look for every program that came with kubuntu-desktop and remove them one by one. That is the most safe way (KDE programs usually have a 'K' in the beginning of their names).
A pro tip: whenever you want to test a Desktop Enviroment, do not install it as recommended in most guides. Google for core/minimal version. The core or minimal versions come only with the desktop, no extra software, making it way simpler to remove afterwards. These versions take a lot less disk space, too. For example, you can install 'xubuntu-core', for XFCE, 'lubuntu-core', for LXDE, 'ubuntu-desktop --no-install-recommends' for Unity, etc., etc.
kubuntu-desktop, which is a metapackage, will be removed. Pacakages installed by the metapackage won't be removed.