public void removeCollisionObject(PhysicsCollisionObject obj) {
        if (obj instanceof PhysicsGhostObject) {
            removeGhostObject((PhysicsGhostObject) obj);
        } else if (obj instanceof PhysicsRigidBody) {
            removeRigidBody((PhysicsRigidBody) obj);
        } else if (obj instanceof PhysicsCharacter) {
            removeCharacter((PhysicsCharacter) obj);
        }
    }
removes an object from the physics space

@param obj the PhysicsControl or Spatial with PhysicsControl to remove
jme3-jbullet/src/main/java/com/jme3/bullet/PhysicsSpace.java