one way I found is to move a building you want to keep and not upgrade to an non serviced area, and wait for it to be unpopulated, then it well never get a upgrade option.
There is a limit thou of about 30 or so you can have like this, not sure if its a % of population, but a got to the stage that houses would not be un-populated regardless on how little services I gave them.
Also this system works if you don't want to start from scratch, but I found wiping a city and starting again does make you a lot of coin, but takes it's time.
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