Final answer:
To disable the integrated UTP network board in favor of a newly installed fiber-optic network board, access the Device Manager, find the network adapter, and use the disable option in its properties.
Step-by-step explanation:
To disable an integrated UTP network board that you no longer need because you installed a fiber-optic network board on your system's motherboard, you should navigate to the Device Manager in Windows. Once there, locate the integrated network adapter, right-click on it, and select Properties. Within the properties window, there should be a tab that contains the option to disable the device. This action will not physically remove the hardware but will prevent the operating system from using it, effectively disabling the integrated network board. Note that the correct option you are looking for will be to disable the device, rather than removing or reinstalling it, running any diagnostic software, installing drivers, or trying the device in another system.