When should I pay off the mortgage?

When should I pay off the mortgage? - 1
Added (1). I have $700K in stocks, my home paid off, two rental income homes one with a note of $243,000 the other with a note of $107,000. I have $100,000 in bank accounts, social security, $2,200, and a great union pension of $3,650 a month. I have no other consumer debt. I want to pay off the mortgages because one will cost $350,000 in interest if paid off through 2043.
Please Help.
Added (2). The interest rate is 5.6% on the larger mortgage.
Added (3). kj566 The rentals are not a headache they have been great income, $2800 a month for many years, Thanks for your answer.
Added (4). Ranger-I-75 thanks for that answer I have a better insight of what to do. I will loose $18,000 interest income write off, but that is only worth the percentage I can write if off on my taxes.
I will pay off the loans and dollar cost average the rental income back into the market. My Vanguard financial advisor is so against this but we know why.

I appreciate all responses guys, Barry

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