OK so it looks like the Sidebar is made up of content within GB Container Blocks.
Edit those Container Blocks – in Advacnced > Additional CSS Class(es) add: hide-on-mobile
more info here on the GP built in hide-on-* classes:
Hi,
Got similar question about a hero image: it looks great on desktop but I want to hide it on mobile so people don’t have to scroll. How could I do this?