What can be used to release the fifth wheel locking jaws for the trailer to be uncoupled? (You should make sure that it is in the engage position and the safety latch is in place.)

The release arm let you disconnect the fifth-wheel locking jaws for uncoupling the trailer. During your pre-trip inspection, if equipped, make sure the release arm is in the engaged position and the safety latch is in place. [Commercial Driver License Manual]