If you have Windows 10, you can go to Settings -> Update and Recovery -> Recovery -> "Restart Now" button -> Troubleshoot -> Advanced options -> UEFI Firmware Settings
Before I had enabled the iGPU, I would see the Asus logo and a line saying how to open the bios. But now I don't see both of these and I can't open the bios
If you have Windows 10, you can go to Settings -> Update and Recovery -> Recovery -> "Restart Now" button -> Troubleshoot -> Advanced options -> UEFI Firmware Settings