@Michael Corona
As other has said, if you have reasonably low rates of interest, it makes no sense to pay them off early. With that being said, there will be a point in your investor life cycle where you have “enough” and are no longer looking to grow your portfolio and want to work toward getting it paid off and enjoy the extra cashflow when the mortgages are gone.
As I have read numerous times from long time investors, there is nothing as comforting as paid off properties. In the early part of your career and the middle is the building time and often you don’t always need the cashflow and reinvest everything to build your capital base. There comes a time in most small to medium sized investors careers though where it doesn’t matter what makes sense on paper, it’s the piece of mind your looking for and less properties that are paid off is a simple way to achieve that.
If you are a financial planner you should already know about the SNOWBALL method, if not google it and you will find many detailed examples. Jeff Brown (Bald Guy) on this site, wrote several articles about similar strategy’s and they are all good reads for ideas.
This early payoff plan also only works if you have strong extra cashflow from multiple rentals after accounting for capex, maintenance and other long term costs that will come up in 10-20 year hold. The only other way to do it is pay the loans down with money from your W2 income if it’s robust enough to support that.