Should you sell stocks to pay off a rental early?

[Eric L Conry]

I have a rental house with 150K left on the mortgage, I have 200k in an after tax brokerage account invested in cash, stocks and bonds. Should I sell the investments (pretend we're in a non-recession normal stock market environment), and payoff the rental? Assuming 15% long term taxes owed I would have to sell 172,500K. The interest rate on the mortgage is 4.3%, 30 years. 

How do you know if you should payoff the mortgage when you have the money, or not?