How do I remove the Header and Navigation Bar from a single page?

which header you need to remove ? Please post your live URL here.

In demo there is logo top search and main menu available So actually what you want to remove

My live URL: https://goo.gl/t1LJW8

I want to remove this: https://imgur.com/7E5XxUh

Open your theme style.css and add this code

.home #header-text-nav-container { display:none;}

or may be your theme provide Some settings from Theme options for hide something.

Just be aware that if you edit your theme’s stylesheet directly, you’ll lose those changes if the theme is ever updated in the future, to fix bugs or security issues or to add new features. Better to use a custom CSS plugin or your theme’s built-in custom CSS option, if one exists.