Shower surround and metal beaded corner

I'm redoing my shower surround with a new tub base and tile walls. I put up my cement board and tape however I have a metal bed of the corner. When installed I put the cement board behind it and figured I would ask about it later. Should I do something like nail the bead to the cement board, screw it with specialty screws, tape and mud it with mortar, or just cut it off?

Thanks for the info.