Trading in a car that I'm financing?

I recently started financing a 2015 Honda Accord in the beginning of the year with a 1.9 interest rate and a 3,000 dollar downpayment. I am paying around 380 monthly, and still owe around 22,000 dollars on the car. I have taken a liking to a smaller 17,000 dollar car from a small dealership that has around 45,000 miles on it. How would trading in my Honda work? Given all the negative equity i have on the car. Thanks!

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