Ask the condo association to handle that. Have them warn the residents and have them acutally turn the valve off. This way if the valve breaks, they did it, not you. When you're done, have them open the valve slowly.
Once years ago at a condo in Palm Beach, FL I showed up to do some work in the parking garage. I had to replace a hose spigot at the base of a 2" copper riser. No pro-press back then. I had to drain the 2" copper riser and re-solder a new hose spigot on at the base which had a 2" x 3/4"x 2" copper tee. Well the condo association maintenance had not warned the residents. So I asked he bldg. manager on duty what he wanted to do. Re-schedule for another day, or shut the water off to the whole place. He decided to shut 'er down so I could get to work.
Wouldn't you know it a lady had dyed her hair and needed to rinse the hair dye out. But she couldn't because the water was turned off right after she put the hair dye in....LOL.
But that could never come back to bite me because I left it to the mgr. to decide that day to shut the water off. It was his call. So that's how you play that call. Let bldg. mgmt. turn water off and on.