Where is the grub configuration file?

[Magic Steve]

I've installed Qubes 3.2 with sys-usb, but found that the USB Wifi I was using was preventing standby and caused problems with attachment/detachment of the device.

Instead, I'd like to use sys-net as the USB-VM, but I'm not sure how.

Instead, I want to remove the sys-usb. I have already deleted it, but now cannot see any USB devices ("lsusb") on dom0.

According to the guide (https://www.qubes-os.org/doc/usb/),I should update the GRUB.

But I cannot find any grub configuration file in dom0 /boot, and also in /etc/default there is no grub file.

What should I do?

Thanks,

MS