Floor Lobby / Passage

I'm staying in a 5 buildings complex, where no co-op society is NOT formed. We have applied for society formation & have a CP & working committee. There are multiple cases going on against the builder in this regards. One of the flat owner is doing renovations. In doing so, he has demolished a common passage wall in front of his flat & built a wooden shoe rack. His argument (suggested by his lawyer) is the common area on the floor is divided equally between all 4 floors on each floor and he can use it for his personal use since he has paid for the common area also! Further more, he says "earlier there were concrete blocks, now there will be shoes in it's place!!!". In fact he has made many internal changes including demolishing some internal walls, enclosing the dry balcony, taking the window grill outside, covering the terrace with permanent structure, etc. My question is, what he is done, is it legally allowed? If not what action can be taken against him? who has the right to do so? Please advise!! Thanks in advance!