There are some types that goes in the category of sacrificing or throwing away your humanity in order to save innocent lives.

Ascension: Becoming a post-human soldier (Adeptus Astartes, Spartans, or any other post-human soldiers)
"They Sacrificed their humanity. To save humanity (or in this case innocent lives)"

Black Rage moments or Converting sorrow into rage: Becoming something that you fear only to protect those that won't fight back.

What are your thoughts? Is it necessary?

3523108
There are still some limits.
I prefer this:

"I lied. I cheated. I bribed men to cover the crimes of other men. I am an accessory to murder. But the most damaging thing of all... I think I can live with it. And if I had to do it all over again, I would. Garak was right about one thing - a guilty conscience is a small price to pay for the safety of the Alpha Quadrant." - Sisko, confessing to his personal log.

- Star Trek: Deep Space Nine "In A Pale Moonlight" [Season 6, Episode 142.]

3523108
I have a better idea, the third option, a nuke, that I must activate, no need to throw away anything except for your body, but your soul, sprit and humanity will be just fine

3549110
Then we lose our morality and later we regret ever designing atomic weapons (if innocent lives gets caught in the cross fire).

[Geneva Convention intensifies]

3523108
I don't really see post humanism as giving up our humanity. As long as their personality isn't artificially altered, their humanity is intact.

3523108

I am confuse on what Post Human is.

On Black Rage it depends on the situation. Like Trebor said it depends on why the individual became what he hates. The example you've shown above is a good one because Eren decided to use his power to protect humanity even if it costs him his own despite the hopelessness around him.

Now I ask you did that make any sense? I am not good at explaing things