Hey there Artnsmt,
How are you doing today?
This could be done with some custom CSS. The easiest way to do that would be to add it in your site using the following plugin
http://wordpress.org/plugins/simple-custom-css
Once the plugin is installed and activated you can add this code to Appearance >> Custom CSS:
.menu, .site-branding {
display: none;
}This should remove the navigation and the logo from your header. If this doesn't work could you please add link to your site so I can take a look? Just out of curiosity how to you plan to navigate between pages on your site if you remove the navigation?
Hope this helps :)
Best regards,
Bojan