In addition to the trunk release button on the Remote Keyless Entry (RKE) transmitter, the trunk can be opened from inside the vehicle by pressing the remote trunk release button. This button is located inside the driver storage compartment, on the left side of the instrument panel.
See Trunk.
Door Locks
WindowsChevrolet Cobalt Owners Manual. Trunk
To release the trunk lid from the outside, use the key or
the Remote Keyless Entry (RKE) transmitter,
if equipped.
WARNING:
Exhaust gases can enter the vehicle if it is driven
with the liftgate, trunk/hatch open, or with any
objects that pass through the seal between the
body and the trunk/ha ...