Unfasten (verb)

1. To unfasten or undo something that is fastened, such as a button or a zipper.
2. To release or let loose.

Origin:

Middle english: from un-1 + fasten.

Examples:

1. She unfastened her seatbelt before getting out of the car.
2. He unfastened the buttons on his shirt.
3. The wind unfastened the sail.
4. She unfastened her hair from the ponytail.
5. He unfastened the leash and let the dog run free.