I recently installed Ubuntu 18.04 on my Dell Inspiron 14″ 5000 Series laptop. And wanted to disable touch screen. After some searching over internet, found following solution. Which works.
xinput –list
Above command will list your input devices, something similar to following.
You will see your touch screen input name. Run following command to disable it.
xinput -disable "ELAN Touchscreen"
I have the same laptop and have no working touchscreen. how did you get it working