May I ask why you got portrait and landscape to start with if you only need portrait?
If you got multiple layouts and want manually to lock one on the fly you can do this by listening to "HypeLayoutRequest". This extension could be a good way to go…
1.) include the JS in your Head-HTML or link it via script-Tag
2.) use the following code on an function running on your first scene
hypeDocument.onLayoutRequest = function(layoutName, sceneName){
return "ENTER YOUR LAYOUTNAME HERE";
}
If this is still to much code for you make your scenario more clear.
I si quieres podemos hablar espaniol.