I put it in my /etc/kernel/cmdline as nvidia.NVreg_EnableGpuFirmware=0 and then ran sudo reinstall-kernels.
For grub system it should be in /etc/default/grub and then in the GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nvidia.NVreg_EnableGpuFirmware=0" after which run the update-grub or the grub-mkconfig command to rebuild kernels.