Take out the primary menu and make it function at top head

Hello again, “Aquí estamos cuestionando” (Here we are asking).

This time I want to take out the menu of the side bar and put it on the top head, as a simple dropdown menu.

But when I tried to take out this, the behaivor of my menu was very weird, because I never could to “hide” the sub-menus.

So, ?Where are the files to modify the position of the menu? Is there any JS relationed directly with this behaviors.

Thankx.