What portion of humanity would you murder if you could?

You have discovered a Mr. Gene Spicer 9000 from the far future, sent back many centuries in time. Unfortunately it has been damaged and the only function it can perform is crafting custom lethal virii. It comes with very simple instructions and a touch-screen interface so easy a child could use it.

You now have the power to craft one or more virii of your choice which will spread and kill any portion of the world’s population you like: by sexual orientation, skin tone, language spoken, age, IQ, ethnic heritage, handedness, eye or hair colour, and so on. Overnight, you could reduce the world’s population to whatever level you wish, including just yourself, if that’s your wish.

You can’t fix the machine, the virus can’t be beaten, survival rate is 0 once infected, etc. Which segments of the human race will you choose to exterminate, if any? And if you choose none, do you accept the responsibility if we destroy all life on Earth due to overpopulation and climate change when you could have prevented it?