Can Kurloz's power can work the other way around too? Like destroying the Rage of others? Or is the Rage aspect only targeted to the Rage player himself?

He actually does both canonically. He Destroys through Rage, by turning Damara’s hatred towards the Session- (Aranea mentions that even with Meenah’s bullying, her behaviour seemed to take such a dramatic, sharp turn that she suspected someone influencing her- And given her allegiance to English, it’s obvious it was Kurloz), and he Destroys Rage as well by appearing super calm and no one from his Session suspects a thing about him, he’s just seen as this harmless weird clown that occasionally flips people off, but not much else.