The lower part of the abs is the most stubborn area to remove excess bodyfat. There are some diet and training tricks to help the process along, but you'll need a workout to compliment your other efforts.
This four-move workout should do the trick of finishing off your six-pack.
Take 30 seconds of rest between exercises and repeat for 2 – 3 sets.
Reverse Crunch x 10
Lie on your back with your arms behind your head, your knees above your hips, and your knees fully flexed. Start by lifting your butt off the ground and then curl your knees toward your head. Return your legs to the starting position and repeat. Keep your knees fully flexed throughout and do not let your thighs go past your hips on the way down.
Deadbug x 10 each
Lie on your back and hold your arms and knees above your body. Extend your right arm and left leg simultaneously while exhaling. Switch sides and repeat. Keep your butt off the ground and lower-back flush on the floor for the entire exercise.
Hanging Alternating Leg Raises x 6 each
Grasp a chinup bar and keep your shoulder taut. Lift one knee as high as you can while driving the other leg downward and hold for five seconds. Switch sides and repeat.
TRX Prone Pikes x 10
Get into a pushup position with your feet in the TRX straps and tuck your pelvis. While keeping your knees straight, pull your hips as high as you can while dropping your head between your arms.