Can convert to store room also. Removed the fittings and no whatever hacking.

if involved tearing down a wall, you better inform MO, there may involve structure damage

as long as no structural damage I dont see a problem inside unit renovation, to be safe, just check with your MO.

Seal the sewage and waste water discharge hole properly. Otherwise the smell and cockroach can enter you unit.

Not possible to change during the construction. If you change, later all other buyers will demand the same. It will lead to a mess & eventually a lot of answering to Local Authority on the deviation from the Building Plan Approval. No way the Architect will allow you do amendment with the risk of the CCC being at risk.

later when you sell the unit, will you redo the toilet? :X