Short of injections with steroids (which I wouldn't recommend) collagen cannot be removed. But then again, it doesn't have to be since it will dissolve over the coming months.The only injectable fillers that can be easily "removed" are the hyaluronic acid gels (e.g., Restylane, Perlane, Juvéderm, Hylaform) by the injection of hyaluronidase--an enzyme that digests hyaluronic acid.
Collagen injected in the nose will eventually resorb overtime. Most of these products will last 4-6 months.