Remove header and navigation bar on single page

Hello!
I am trying to remove the header and navigation bar on a landing page. I have tried a few different things, googling custom CSS, looking through this forum, but I have not found a solution. Could you help me with this?

Landing page URL is: http://www.kristianglomset.no/gratis-provetime/

Please see attatchment for screenshot of area I want removed, it is higlighted by the red box/lines.

Any input would be most helpful 🙂