You are trying to use a function that exists on the NodePath class, but you are calling it on a BulletCharacterControllerNode, which does not have that function. If you take a look in the API reference you will find what functions exist on each class. I recommend taking a look through the API reference and in the Bullet section of the manual which seems to be well written.
I think the issue you are having is confusion between a “NodePath” (which is used to rotate and move something around), and a “node” (such as the character controller) which is the visual or behavioral part of an object.