The key is used to remove and insert the lock.
Use this SY-ACC20222 port blocker to prevent other devices from being connected to the system.Features a key and lock assembly - the lock plugs into the USB port preventing access. Syba SY-ACC20222 4 Piece USB-C Port Blocker with Removal Tool. The port blocker includes a "key" which is used to lock in and remove the USB-C blockers.