How to remove Buddypress menu items from Blogs MU theme?

Hello,

My URL is http://www.thecommute.co.uk/. I am using Blogs MU theme and recently I have installed Buddypress.
I have problems with Buddypress menu items on the top of my site (Home, Activity, Members, Groups). I want to remove this menu and use my own menu.

By the way, these menu items redirect using wrong URLs. For example, there is http://www.thecommute.co.ukactivity/ instead of http://www.thecommute.co.uk/activity

Thanks,
Stuart