Make the pleasure of life.
The bump nose looks very angry and unfriendly. It is very common in western countries and it looks nice and suitable on Caucasian prominent face. However, it looks not so good in eastern flat and round face.
Surgeon should decide how much bone or/and cartilage or/and septum should be cut and removed, based on how much the bump is.
If more bone, cartilage, as well as septum will be removed, the open roof should be closed well.
The surgical method is to break the lower part of nasal bone totally and keep the connection on the upper part, which seams like the greendstick fracture, and then to push the nasal bone medially.