just figured this out the other day, also got confirmed by another gigabyte owner

• Reboot to UEFI BIOS shutdown /r /fw -t 0
• Go to Settings > IO Ports > App Center Download & Install Configuration > Disable
• then simply uninstall App Center from Add or remove programs
• to be sure that everyhing is uninstalled you can
• delete adjustservice.exe with sc stop MyService1 && sc delete MyService1 (open command prompt as admin)
• then delete the C:\Program files\Gigabyte\App Center folder, it might be under (x86)

gigabyte seem to be lazy calling the adjust service for MyService1