Spoiler, it was through earning, saving, and investing. But the details are more interesting.
We purchased the home in late 2013, lived there for a year while renting out our prior house. The first year allowed us to get "primary residence" financing with a low interest rate and smaller down payment. We then moved back to the old house and brought renters in. I saved up some more money over the next year or so before another real estate opportunity came up. This one was key.
I purchased the third house in 2015 undervalued, but in pretty bad shape and with a terrible tenant. The tenant was evicted after only a few (painful) months and I went to work on a quick rehab to get some nice renters in there. After another year lease, my tenants got divorced and moved out. The market had really heated up, so I decided to finish off the renovations and sell.
About the time the rehab house sold, we moved back to the original home. I took the proceeds from the sale including my down payment, the renovation costs, and about 40K in profit and paid down the mortgage. Another 6 months later (today) and I've just made my last payment.
Do you have a plan to, or have you already paid off a mortgage? How'd you do it?