how do you remove the post reply form

It’s done on a page by page basis. In Admin Section, identify the page you want to remove the form from and selecte Quick Edit. Ensure the Allow Comments box is not selected.
Update the page.

There is an option called “discussion” that may be hidden in your page editor. You might have to activate that option (see upper right when editing the page). When active, you get an additional box where you can select whether to allow replies and trackbacks.

Took me two days to stumble across it 😉