Vauxhall 2013 Corsa Owner's Manual page 142

Driving and operating 141
Dismounting the coupling ball
bar
Insert the key in the lock and unlock
the coupling ball bar.
Push the rotary knob onto the
coupling ball bar and rotate right while
pressed down until it engages. Pull
out the ball bar downwards.
Insert sealing plug in opening for
coupling ball bar. Fold away socket.
Place cover on bumper and push both
bolts outwards.