How do I customize the themes menues?

So I’ve installed the Bp-daily theme on my new wordpress website and the menu bars consist of 3.

1st row seems to put categories there.

2nd is the only you can manually control.

3rd seems to be buddypress related pages.

Ok so the thing is that I want to be able to have full control over all the menues. I want to be able to have only 1 or 2 rows if I so desire. A feature the theme options currently lack.

So how do I customize to my liking? for example I want to get rid of the categories row (and possibly merge the buddypress links with the other menu.)