None of us on this forum are permitted to represent HP regarding warranty issues.
I would say that if you didn't break anything when you removed the discrete video card, that the warranty would not be voided.
If you decide to remove the video card, first go to the control panel>programs, and uninstall any nVidia programs you see listed there.
Then go to the device manager, click to expand the display adapters device manager category.
Right click on the nVidia display adapter and select Uninstall. Also check the Uninstall Driver box.
Shut down and unplug the PC, press the power button to drain any residual electricity from the motherboard, remove the video cable from the graphics card, and remove the graphics card.
Then connect the video cable to one of the onboard graphics ports, hook everything back up and when you are in Windows again you will need to install the Intel graphics adapter from your PC's support page.