Nvidia Optimus Not letting me start games

Model number of the laptop would help but on my packard either you can open intel integrated graphics settings and turn off "switching gpu to save power" or goto the power settings and turn off the change graphics card to save power.

Right clicking on desktop and selecting "configure switchable graphics" also works on my machine

Most laptops switch to dedicated gpu if you switch to high performance mode setting so try that as well...

Edit:I read that some of the newer laptops have a Fn key+dedicated button to switch between gpus, search if that applies for your model

http://www.tomshardware.com/answers/id-1988136/laptop-dedicated-gpu.html

while this info is for autocad, this page has a nice screenshot of switching the gpu in nvidia settings

http://knowledge.autodesk.com/search-result/caas/sfdcarticles/sfdcarticles/Crash-on-systems-with-integrated-Intel-HD-and-discrete-GPUs-Nvidia-AMD.html