You've got about $44,000 in equity and you're cash flowing around $400 per month (I'm assuming some repairs/maintenance/vacancy).This means you're getting a return of over 10% on your money right now by hanging onto this property and renting it out.As the other posters have said, probably best to hold this one as a rental unless you think you can do better than 10% with another property.

@Christian Francois, to give you a cost breakdown on how much it is to obtain a license and hang it with a brokerage; ~$300 for the real estate course, ~$200 for State and National Exam, ~$150 for the Real Estate Commission to activate your license, ~$500 annually for NAR membership, $X per month MLS fee, $X per month in broker fees, commission split with the brokerage (80/20, 70/30, 60/40), etc.

My understanding is that here in California, a broker's license permits an individual to operate independently without having to hang their license/be affiliated with another brokerage firm. 

According to my AirBnB clients (many of which are much more successful than I): They'd be good properties to hang on to in the short term.

There are also rather good looking hanging panels you can hang from the ceiling (vs a permanent attachment) that will absorb and minimize the sound transfer.

@Joel Case  Hang in there.  

Ordinary wear-and-tear would include a couple small nail holes to hang art or family photos on a wall.

I've got guys that are working 300+ feet in the air in a basket held up by crane with a welder. 

Hanging on to a negative cash flow situation and feeding it from your wallet every month is called an Alligator.

Only difference is less cash back.Part of me wants to hang on to the properties for equity growth, essentially just let the tenant pay for my mortgage and equity growth.