Can I release my pet into the wild?
Turtles in pet stores are often not native to this area or even this part of the country. The Red-Eared Slider (one of the most common in petstores) is a southern species and wouldn't last long in New England.
Releasing pet turtles is very dangerous to both your turtle (it will probably die) and to the native turtle species. A turtle that is in captivity does not know how to survive in the natural world and will almost always die. The native turtles could possibly get sick and die if they come into contact with your released pet. Pet turtles can carry diseases that Native turtles cannot cope with. There are several instances that an entire local area's turtles were wiped out because of a pet turtle that was released.
Can I release my pet if it is a native turtle?
So your pet was once a wild turtle? While it may seem like you could release the turtle back to where you found it, there are many issues that complicate this. To avoid risking the life of your turtle or spreading diseases to wildlife, contact the Turtle Rescue League or your local wildlife rehabilitator. They can direct you what to do with a native pet.