Yes you need to take a permission from the municipal corporation as you are removing a wall between 2 bedrooms. Please understand, if you take permission it’s better. If you do no take appropriate permissions from society secretary and municipal Corporation then in future municipal Corporation might send you notice stating that this change was contrary to your original sanctioned plans for the flats granted by the municipal Corporation. You do not require permissions for refurbishing your house which is floor repairs, walls paints etc. But for removing a wall you will require a permission. And once it is granted they will never trouble you. Or else they would send you notice for getting the flat back to it’s original plan or they would break it. And society or any member in the society have rights to complaint against you as well.