I was given a bonsai as a gift. I am not that interested in devoting the time it takes to properly take care of it. I would rather replant it, and just let it grow naturally. Is this something feasible to do?

If you are in an area that have suitable climate for the species it is absolutely possible. We all do it from time to time to speed up development.

Where do you live and what species do you have?

Sure. If it is a species that can survive in your climate. Naturally, this will then turn into full grown trees.