Can i let my zebra finches go?

Do NOT release them into the wild! You are responsible for those birds so you will have to find a place for them. Whether it be the humane society or a local who is interested in them. There is no telling what will happen if you release them into the wild. They will either be killed, die because they do not know how to fend for themselves or actually survive and over-populate the local area.. POSSIBLY over-running and ruining the local eco-system!