[Closed] Poly Normal selection?

Hi everyone i’m a newbie in max, because a project I’m involved I’ve learned to model in this great software, the thing is that I have to model a lot of buildings but i have to erase all the faces witch have their normals facing upwards (to the positive side of Z ) so the first thing in my mind was that there might be a way using maxscript to do this and might be not to hard. The thing is that I’ve never used it and I’m in a hurry so if someone can help me it’ll be very appreciated. (or if someone know a better way to solve this problem it’ll be very much appreciated too)