Kubuntu to Ubuntu

Is there a way to switch from Kubuntu to Ubuntu?

I tried to search with add /remove and on net but always get Ubuntu to Kubuntu not otherway around.

Simplest way:

sudo apt-get install ubuntu-desktop
sudo apt-get --purge remove kubuntu-desktop
sudo apt-get autoremove

Here is a good place to research this kind of switch.

ubuntu-desktop (jaunty) and kubuntu-desktop (jaunty) are meta-packages that will reference all of the packages needed to run their respective desktop environment (including default applications).

When it gets to the point of installing gdm (gnome display manager) it will require some input from you. If you're plan is to remove KDE and KDM for good then let it switch your default display manager to be GDM.

By using the --purge flag you are removing all configurations for that package so any future install of it you will be starting from scratch. As was pointed out in a comment using the autoremove is how you tell apt to remove all orphaned packages that would have depended on the kubuntu-desktop and that should get rid of most (if not all) kde/kubuntu desktop apps.

Here are 2 SuperUser questions that might also be informative. Question 1, Question 2

Install the ubuntu-desktop package. This will install all Gnome requirements.

sudo apt-get install ubuntu-desktop

After installation is complete, logout of your kde session so you are at the login screen. There should be an "session" icon somewhere on the screen. Click it, and select "Gnome" instead of KDE. Now when you login you will be in the gnome desktop. If you want to make this move permanent, follow jtbandes advice.