WARNING: This page is about a different car, the 2016 Hyundai Elantra GT and 2015 Hyundai Elantra GT. However, it is still accessible from the selected car via links, so may be relevant.
Fully extend the piston rod.
Drill a hole on the (A) area to remove gas from the cylinder.
Fig 1: Drilling Hole On Area
Courtesy of HYUNDAI MOTOR AMERICA
CAUTION:
The gas coming out is harmless but be careful of chips that may fly when drilling.