Hi there,
go to Customizer > Layout > Container and set the Mobile ( click the icon ) Padding to 0
Or what we recommend when using a Page Builder or other tool to create full width content is to set the Container Container to Full Width:
https://docs.generatepress.com/article/content-container/
This also removes any theme padding – so any pagebuilder content will span the width, means you don’t have to use stretch options in your builder 🙂