I'm using Ubuntu 18.04 with kernel 4.15 and installed Nvidia driver 418.67. All of this is installed on the new Razer blade advanced 15(2019) model. When I change to Intel and reboot powertop says its drawing out 40-50 Watts idle and the Nvidia device is not turned off. I've tried a bunch of workarounds including tlp and https://github.com/timrichardson/Prime-Ubuntu-18.04. Afterward doing these tweaks idle draw is around 17-20 Watts. This still seems a bit high and furthermore issuing the commands.
sudo -i modprobe bbswitch cat /proc/acpi/bbswitch
it says 0000:01:00.0 ON, so the Nvidia card is still on. Furthermore powertop also confirms that an Nvidia device is still turned on. Can someone please help me to figure out how to completely disable the Nvidia card in Intel mode.