Removing VSCode Code Margin
I believe what you are referring to are the "sashes" coming from the "centered layout" view. To remove them just uncheck that view (on Os X it's under View/Appearance).
https://code.visualstudio.com/docs/getstarted/userinterface#_centered-editor-layout
Search for "ruler" as suggested here, Click on the link to edit the .json file, you can comment the "editor.rulers": lines.