"I'm not growing nerves with. And since I can shape it..."

It's still growing, but as it does, it starts getting pretty thin around the base. Sadde holds it with his hands, and by the time it has stopped growing it's only technically still connected to the bone on his forehead. He uses that connection to reshape the base so it looks like it's been sawed off, and then he snaps it off, wincing very slightly. The exposed bone of his forehead returns to its old regular shape, and his skin starts knitting itself back very neatly.

"Ta-da!"