Place a stool on the floor near the window to reach the locking pin if necessary.
Grasp one locking pin with one hand and press the window down or to the side with the other hand to take any pressure off the locking pin. Pull the pin out of the bracket and let it dangle, then repeat the process for the other locking pin.
Unfasten one small diameter chain with a screwdriver and place it on a nearby table. Then unfasten the other small diameter chain with a screwdriver. If the chains will not pull away from the wood window by hand, use a putty knife to pry them off the window frame.