First of all, the ego can't be killed, because it's not real. It's something you do, rather than some noun to kill. It's you, grasping for the world, pushing away the world, in the form of "I am a person," "I am lazy," "I want a house," "I don't want to feel bad." Stop grasping and pushing away TOTALLY, and that's the end of the myth of the ego. That's when you see that you've made this WHOLE thing up, in totally innocent ignorance.

"Wouldn't killing it defeat the purpose of experiencing a separate reality?"

No, yes, sort of. But when you've been dreaming for millions of years, you're going to want to wake up at some point. Especially when the dream starts to get really shitty.

Or, from another perspective (and one that seems more "like it") the end of the dream of "separate reality" and me vs. you or me vs. the world is the next level of human evolution. Understanding who you are, beyond all of this, and living AS the integral flow of life itself is intelligence defined, transcending anything we currently call intelligence or knowledge.

"Don't higher beings also have an ego of sorts?"

Of sorts. The involuntary and confused grasping/pushing away isn't something they do. They do it knowingly, totally aware that it's just for fun and a game and never, ever serious. It's pretending to be a person with opinions, desires, or ideas - typically for the sake of those who still think they're actually really people with opinions, desires, or ideas. Or just for fun.