Cannot get rid of nvidia drivers, restore nouveau driver and get desktop working

I made the mistake of installing the Nvidia Linux drivers direct from their website.
It failed because it could not remove the nouveau driver.

Next I manually installed the nvidia drivers from the repository which successfully installed the nvidia driver, but the Ubuntu desktop does not function; no launcher, no menu bar, no windows. (Gnome seems to work though).

So I want to revert back to the vanilla installed nouveau driver.
I tried

sudo stop lightdm
sudo apt-get purge nvidia*
sudo apt-get install xserver-xorg-video-nouveau
sudo rm /etc/X11/xorg.conf
sudo reboot

but lshw -c video reveals I still have one nvidia driver and one i915 driver.
nouveau has not returned and the desktop will not function.

I am considering a complete reinstall, is there anything else to try?

I have followed the other threads with the same issues, but the solutions did not work

sudo dpkg-reconfigure xserver-xorg

Creates an error.

sudo apt-get install --reinstall xserver-xorg.core libgl1-mesa-glx

Did not make a difference.

cccm

Same.