does anyone know how to "blast away the wall" in "Whomps Fortress" for Super Mario 64 DS?

Answer 1

Unlock the cannon, and then get inside of it. If you look off to the right of the cannon there's two walls pointing out and a hill with a red coin on it. Aim yourself towards the corner of the wall farther from you and shoot, if you hit it right it "blasts away" the corner of the wall and unveils a star.

Answer 2

I think you have to aim in cannon at the sharp section of wall that is situated next to the rotating walkway, at least thats what you do in Mario 64 for the N64 version

its the section of wall that is right next to the rotating walkway thing that you use to cross to get to the boss

hope that helps