The building does not like to have to turn of the water to everyone just so you can work on your plumbing.....not your fault because it was built that way. They are asking you at the time of your remodel work to install an accessible valve(s) to turn off the water to your bathroom. From a practical standpoint, that may not be possible, but for sure you should purchase a shower valve which has hot and cold stops built in. That allows it to be serviced without turning off the building. Your sink and toilet already have individual valves, presumably.