To edit a curtain wall element select it and click on the 'Edit in 3D' . pop-up tag.
Adjust the polyline that defines the bounding of the frame; this is easiest with just the Scheme showing.
To trim a CW you can use either the Trim to roof or SEO commands.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"