Generally there is no need need to disable any Integrated Graphics Chipset when using a discrete Graphics Card.
The Graphics Card's drivers will differentiate between the Chipset and the Graphics Card and will always prioritise the Graphics Card if one is one detected on system boot.
Furthermore it can be risky to disable Integrated Graphics as, in the event of a GPU failure, your fall-back graphics option is not immediately available, which can cause all kinds of complications.
There shouldn't be any reason to disable a correctly functioning Integrated Graphics Chipset.