Hi,
Once you enter the bios, press 'F7' to switch to advanced mode and check for the boot menu tab at the top, but notebooks don't have a setting for the Boot Logo Display unfortunately.
If you check under the 'advanced' menu at the top, look for the 'Animation Boot Logo Configuration' setting to disable the boot up sound, but it doesn't stop the ROG logo from appearing at boot up.
You can also disable the boot up logo sound in the Armoury Crate System Configuration on the home page.
Hope this can help some.