There are multiple versions of that laptop (that isn't the full make/model) so I it is hard to give exact info. Additionally, the manufacturer states there are a few versions of the GPU that can go into that laptop.
And you can attach an external monitor to the laptop and set up which ever graphics on the laptop you want it to use. But the same can be done with the attached display. You just have to choose which graphics you want used for which things.
That said, I am not sure why you would want to not use the GPU or disable the GPU which would be the better graphics on the device.