Because there are so many possibilities when importing bbpress into all themes, there is currently to ‘automated’ way of removing the sidebar in the theme. (really we can’t control that part)
What you can do however, is follow #3 in the thread:
https://bbpress.org/forums/topic/bbpress-20-theme-compatibility
That will get all the bbpress theme files into your theme where you can then modify them.
At that point you could remove the call to the sidebar in all the templates for bbpress and your good to go.
