System76 Boring Backlight, how to control it?

I ever dislike the keyboards with lights, today after firmware update on my NS5x_NS7xPU the keyboard..become "with backlight". How to turn off? I have tried this command as root sh -c "echo 0 > /sys/class/leds/system76_acpi::kbd_backlight/max_brightness" sh: line 1: /sys/class/leds/system76_acpi::kbd_backlight/max_brightness: Permission denied When I press fn+f7 it appear a "monitor configuration" of Xfce4 When I run this command echo 0 > /sys/class/leds/system76_acpi\:\:kbd_backlight/brightness the keyboard backlight is still on,