New homeowner of a condo and have a problem with single handle shower faucet sticking. It's really hard to pull out. Can I fix without turning water off? Problem is that water shutoff is a single one to the whole building -- have to give 48 hours notice and inconvenience my new neighbors.
That is a Moen brand shower valve. It has a cartridge (plastic or brass) that inserts into the valve body, retained by a "U" shaped clip. The cartridges get sticky over time which can be remedied with waterproof plumber's grease but I would probably replace the whole cartridge.
The water needs to be turned off but you may be able to do it right at the unit. Smart builders/plumbers frequently install shower valves with built-in shut off valves, for apartments and condos. These are called "integral stop" valves.
Remove the knob and trim plate to see if there are integral stops on the hot and cold water supplies, they will be a part of the shower valve and will look something like this:
The small stems with the slots are the stop valves, which can be operated with a screwdriver. If you do not see the integral stops, the main water supply needs to be shut off prior to servicing the cartridge.
Most showers do not have shut off valves like sinks & toilets do. I would check with the building manager or maintenance person (sounds like you did this). When you disassemble the valve to repair it water will flow unless turned off. so the answer would be No the water needs to be turned off to repair the internals of a valve.
A throughly equipped modern plumber (or a seriously motivated macgyver DIYer) could improvise a shutoff where no shutoff exists by freezing a section of pipe.
The DIYer would have to rent one of those if the local tool rental has one, or kludge up a way to hold an ice/salt mixture around the pipe until it freezes.