Theme: Redesign

Hi, I am a new WordPress user, and am trying to make the redesign theme suitable for my goal. I would like to get rid if the extra sidebar (the outer right column) on the page bpml.club. I have no use for it, and it takes up a lot of space. I might need to stretch the width of the left (main content) column also, but I am not sure. I can’t seem to find any clues on how to do that. Is that so very theme-dependant? Hope someone here can help. Thanks!