1) Put rent controls in place. (And, BTW, encourage people not to work, and give benefits which reward the destruction of the two parent household; lower school standards and pass everyone no matter what.)

2) Unable to perform maintenance and comply with regulations while making a living, rentals dry up and landlords get out of the business in rent controlled areas. Or, black market leases develop. For example, if rent goes up only when the tenant changes, then the tenant never changes; the tenant becomes a middle tier landlord, subletting sometimes legitimately, but often in breach of their own lease.

3) Governments take over or build "projects" under laws which exempt the government from those maintenance regulations that were imposed on private landlords. People forget this part: the government always exempts itself from its own regulations. That's why the government projects are always worse than the apartments they replace. (I wouldn't get any food from a government run grocery store, since they likely won't have to comply with food safety rules that private stores will comply with.)

4) The "projects," while being useful for Democrats since they often create situations in which people are sorted by race, will eventually deteriorate. They become a hotbed for crime and general unsafe living. It may take many years, but the projects are eventually closed down, and in some cities they are demolished. NYC may not demolish them, though.

5) Either
(a) the city stagnates and then ceases being a place where people want to live, and you get collar cities around the rotten, dead city core (and attempts to revitalize the core are fought as "gentrification" which is deemed racist), or
(b) voters eventually elect a law-and-order, capitalist mayor who puts things back on track.

6) If 5(b), we eventually start over at (1) since the electorate has a short memory when it comes to socialism/communism, and since Democrats go out of their way to register people who are too lazy to register themselves, or they harvest votes or solicit mail-in-ballots from people who are too lazy to go vote on election day (and who, by natural extension, are too lazy to inform themselves about historical trends and modern issues, so they never go beyond the promise of free stuff because they don't realize that there really no such thing as a free ride).

----Grossly oversimplified, but you get the idea.