How-to unlock and re-use a zip tie (cable tie): Life Hack #1
Be careful with the pin, don't pierce your finger!
This video shows how to unlock a zip tie/ cable tie easily using a safety pin. Insert the pin in the gap where it locks to the teeth (don't use a thicker pin, otherwise it may bend or break and the zip tie becomes useless. Keeping the pin in there push the tie in the opposite direction to open the lock.