Is it possible to sell fish back to pet stores like petco?

i own a 29 gallon tank with 10 mollies and 5 neon tetra. I am planning to make it more of a community tank by removing fish and making it all females for no chances of mating. I also want to add MORE fish to the tank.My only issue is removing fish without selling them on the internet.(Too young for that stuff.) Is it possible to give fish or sell them to stores like petco or walmart?