How to disable the Primary Menu

Hi, my website is http://providencehomeimprovements.com/ and I would like to have only the secondary menu appear on the site. I can make the secondary menu disappear by hitting only “Select” in the menu selection box in the Customize screen, but when I choose this option for the Primary menu, it defaults to the same menu that I have selected for the secondary menu. I tried creating a blank menu and setting the primary one to that, but the primary menu (now blank) still showed up in certain screen widths. I would like to (not permanently, but be able to turn it on or off) remove the primary menu from the site and use the secondary one instead (as the main menu, because I like how it looks). Is this possible? Thanks. Great theme, by the way.