you can activate the slideout navigation for desktop and mobile.
Then to remove the horizontal primary navigation just create an empty menu and assign that to the Primary Navigation.
and turn it on. Than just choose, on which side you would like to have it. Than go to Design –> Menu –> and assign your specific Menu to Slideout Menu position.
I visited this website wpleaders.com a few weeks back and it uses GeneratePress and I really love the menu style it has and want to know if it is also possible for me to create the same menu style for my blog or is this something very complicated? Also note that I am using the header widget for my logo and menu. Any suggestions?