Leviton Dryer Outlet, NEMA 14-30, Black Plastic, 30A, 250V AC, Compatible with Dryers

How do i wire this with 10/2 romex? black and white go to x&y with ground going to w? then at the circuit black and white go to double pole breaker?

I have a old power cord that I cut the end off and have the plug part can I use this to a 120V 15 amp for a electric dryer?

How do I remove the button on the mount. The box says to remove knockout hutton but how?