Do you mean in a socialist government? Or working with the system we have now?

If it's the later, I mean what Portland did seems to have worked. Drew a line around the city and banned suburban sprawl behind that line. While that won't eliminate already-existing suburbs, it does prevent the problem from getting any worse. If it's a growing city then it forces people to revamp brownsites. If you want to actually "eliminate" suburbs, I think it would largely involve what I described plus changes in zoning and massive investments in public transportation so people could reasonably get by without owning a car.