Manually un-cocking your crossbow is something that is not recommended for all hunters. This is due to the amount of force that is released once you have pulled the trigger. If you are unable to cock the crossbow manually, it is STRONGLY recommended that you don't try to un-cock it manually.
Step 1. Visually and with your finger, ensure that there is no bolt on the crossbow deck.
Step 2. Place your foot securely into the stirrup, with as much downward pressure as possible.
Step 3. With both hands, firmly grab the string on both sides of the deck and draw it back into the locking mechanism.
Step 4. Once you are holding all the pressure from the string, turn the safety mechanism off.
Step 5. Pull the trigger with your finger, thumb or better yet, have someone else pull the trigger for you while you focus on holding the string.
Step 6. Once the trigger has been pulled, slowly advance the string along the deck until it is in the rest position.