Disabling the DE & LightDM in Debian for the nanopi 2

Hussam
Hello, I'm running the Debian build on the Nanopi 2 and was wondering if
there's a way to disable the Desktop Environment, the vnc server and
Display Manager altogether. 

I'm interested in using a purely headless cli setup. 

I tried disabling them via systemd (systemctl disable/stop lightdm) but I
got an error due to the custom init scripts, and lightdm started up
anyways.

Hussam
The exact error that I get when I attempt to disable lightdm (or
tightvncserver) as root is as follows:

"Synchronizing state for lightdm.service with sysvinit using update-rc.d...
Executing /usr/sbin/update-rc.d lightdm defaults
*** Error in `systemctl': double free or corruption (fasttop): 0x0007fa28
***"

The command that I use to disable lightdm/tightvncserver is:
'systemctl disable lightdm'

I run the command as root

jjm
hello,
     You can try to do such as: 

apt-get remove fbgrab
apt-get remove grafx2
apt-get remove pcal
apt-get remove mupdf
apt-get remove geany
apt-get remove gpicview
apt-get remove hardinfo
apt-get remove smplayer
apt-get remove synaptic
apt-get remove gedit
apt-get remove tightvncserver
apt-get remove lxterminal
apt-get remove iceweasel
apt-get remove iceweasel-l10n-zh-cn
apt-get remove lxde-core lxtask lightdm xinit

   But I have not done one actual test.