Ditto fastfly's post. Never put things from your aquarium into the wild; it can become an invasive species or simply introduce parasites/viruses/bacteria that the native population has no protection against. Like fastfly said, it's bad.
If you don't want the snails, you can lure them into one spot using a piece of lettuce, spinach, or cucumer. Once they gather on it (leave it overnight and remove in the morning is a good way), simply remove the veggie and any snails near it. If you see egg sacks, just smush or wipe them away. Also, make sure not to overfeed since that will make them breed like crazy. If you feed an appropriate amount, then they will not breed at nearly the same rate.
I like having snails for the same reasons as fastfly except the fish that eat them for me is my figure 8 puffer, and I have to remove the snail from the freshwater tank to the brackish tank the puffer is in. Some people like to use them as sort of a canary in the fish tank where they know they are overfeeding if the snail population starts increasing.