1. How do I Manage Hide/Show Sections in Layout Manager
In WordPress Dashboard go to Appearance submenu and click on Customize.
After clicking on customize you will in theme Customizer.
Here you have to click on Theme Layout Manager.
You can enable and Disable the Layout Manager by Drag & Drop Sction.
Go to Customize -> Theme Layout Manager -> Theme Layout Manager -> Enable & Disable Here.
2. How to Manage Theme Sections Layouts
In WordPress dashboard go to Appearance submenu and click on Customize.
After clicking on customize you will in theme Customizer.
Here you have to click on Theme Layout Manager.
Here you have to Drag & Drop Section According to requirement.
Then Click on Publish button.
Go To Customize ->Theme Layout Manager-> Drag & Drop Section Here.