Hide main menu & use use top strip menu as main?

To maximize my screen real estate on our new site, I would like to hide the main menu completely and use the top bar menu position as my “main” menu. But I can’t find any way to do this within the style and menu options that are available. On the Manage Locations tab of the menus page, the only options are existing menus. There’s no option for “no main menu” or “hide main menu” If I try to use the “-Select menu-” option to not select an existing menu, my home page totally freaks out, so I guess that’s not a valid option.

Is there a standard way to do this that I’m not seeing? Or is there some quick CSS I can drop in someplace to make this happen? I can use that main menu depth for more important things on our site.

Thanks! . . . Dave