Some sentence examples which use the word 'unfasten'
She began to unfasten her long braids.
For answer Zeb began to unfasten Jim's harness, strap by strap, and to buckle one piece to another until he had made a long leather strip that would reach to the ground.
Once your ship is down on the dock, unfasten the belt, get up, and go Starboard into the storage room.