Yeah, as mentioned, there are options to make your workflow better if you want.
Uncheck the 'generate RealCharts', as mentioned above, will get rid of the bottom un-needed tracks issue.

The 8 'BB' tracks (with the blue track names) at the top are the designated BiaB tracks.
These (if left as is) will regenerate the whole song when the Song Generation feature is used; much like BiaB does. This retains a BiaB behavior if you want it. It takes longer in RB but the behavior is retained.

Some people use them, some people delete them, personally I just use Right-click - Tracks - Make all BB tracks regular tracks.
Then those blue track names turn black and the tracks act like normal RB tracks. You can do whatever you want with them.
They are not permanently locked as BB tracks, they just start that way IF you open an BaiB file. When you open a BiaB file RB does as much BiaB adaptation as possible .. but it's pretty easy to get rid of if you want to, which I normally do right away.

If I open a BiaB file, the first thing I do is Make all tracks regular tracks.
If I wanted BiaB behavior I'd be using BiaB ... but that's just me.

I do not work here, but the benefits are still awesome
Make your sound your own!