Most owners of MBPs from 2010 with an apparently flawed NVidia dGPU should not seek to disable the GPU.
While that circumvention is possible – either electrically, or with EFI/NVRAM hacking, or with moving the video driver kexts related to the NVidia-chip, it is by far not the best solution.
On most of these models it is not really the dGPU that is defective. It just appears like that because you notice the problems when the dGPU is 'switched on'. It is entirely possible that indeed the NVidia dGPU might be defective. But in reality it is most often only a tiny little capacitor that really has a flaw and interferes with power management of the dGPU.
If the capacitor is the problem, then one 'halfway' good solution is to circumvent the most problematic part of power management by lowering the power allowance for these dGPUs. That can be achieved by altering the kext
AppleGraphicsPowerManagement.kext. That can be made easier by using a ready made patch for that. Performance will be a bit reduced by that.
MBPMid2010_GPUFix is an utility program that allows to fix MacBook Pro (15-inch, Mid 2010) intermittent black screen or loss of video. The algorithm is based on a solution provided by user fabioroberto on MacRumors forums.
If that is the case, then a good, and permanent, proper, fix would be to replace the cheap capacitor. Apple will not do that at all out of a bizarre principle and Apple also forbids AASPs do this kind of repair (the machine in question also is way out of warranty and AppleCare). That means owners holding on to these machines have to look for a trustworthy hardware repair shop that is not an AASP and willing to do this. The cost for the parts will make you laugh with tears. More information for this can be found in this rather long thread or in this amusing youtube video.