Hide menu when page loaded - in bootstrap with toggle colapse menu, left right @ mobile [on hold]

I found this menu template in bootsnipp which works fine, except on mobile, I mean when page is loaded, both menus are already in the screen, and I would like that they are hiding when the page is loaded. I'm having troubles in understand the javascript function, in other templates I've seen the "show/ hide .collapse" or the "hidden".

Could anyone be kind enough to help me fixing this feature?

Thanks a lot.