Most likely you won't have a choice - taking units off the market is very difficult. Assuming you could and that you are asking under the context of selling, it seems hard to imagine a scenario where selling multiple units in a price range that more people can afford would net you less than selling to one buyer in a much higher price range, not to mention potential costs of coverting to a single family. However it depends a great deal on how many units you are talking about. If it's two units these are in high demand providing there are no eviction history issues, but 3 or more will require fractional loans and currently (as of last month before I left the country for a bit) Sterling Bank was the only retail lender of those kind of loans and that is making many buyers skittish, particularly with rates on conventional loans so low right now.
I would first determine the possibility of converting - as others have pointed out a good first step is looking at the 3R report, and if you don't have one they can be ordered on the 3rd floor of the building dept for $160 - but don't rely solely on that as they are often inaccurate. If you actually get to the point where you can do it then I would recommend you consult with at least two reputable agents/brokers and get an idea what sales prices would be in the multi-unit vs sf home scenario before making a decision.
Lance King/Managing Broker