Hey @Keita R. Eaddie, welcome to the BP community!
Like others have mentioned here, it really just comes down to the numbers (and your goals). Make this as scientific as possible.
STR:
$500/mo cash flow. What is your capital investment in this property (downpayment, closing costs, capex since buying)? Use that to calculate CoC.
Sell:
What is the ROI on paying off your debt? In other words, what is the interest rate? Is this better than the CoC you see from STR? How much do you have left over after paying off debt? What could you do with that? Remember Atlanta is pretty expensive now and a very tough market, especially for new investors. How much time and effort will it take to find something that produces a better return than the STR strategy above? "Flip the money later in other real estate properties" is not a solid enough plan to choose the sell route. That is not scientific at all and just you guessing/hoping.
Refi/HELOC:
Have you thought about this route? Since it's still your primary residence, you can refi at favorable rates and are still able to pull out a line of credit with a HELOC. This may allow you to pull out enough to pay off your debt and still allow a small amount of cash flow. Again, it's all about the numbers. If that HELOC has a higher interest rate than your debt, this wouldn't make sense. If the new mortgage has payments that put your cash flow in the red, this also wouldn't make sense.
Personally, I would take cash flow now, rather than cash. With inflation through the roof, having money in cash flowing assets with low rate debt would make me much more comfortable than having a pile of cash. But others would say take the cash because opportunity is on the horizon with a likely downturn coming. Only you can really decide what's best for you and your RE goals.
Hope this helps a bit thought. Please, feel free to reach out anytime if you have other questions or just want to chat!