Is it possible for a guy to get 6-pack abs or at least a flat stomach by working out and doing ab exercises?
I’m 18 and I work out on a regular basis – abs, biceps, triceps, chest etc. I am wondering if continuing to follow my workout routine will eventually cause the bit of fat around by stomach to disappear or is cardio necessary or something else also necessary?

cardio is necessary too. it burns the fat off your stomach and under the fat is where muscle is. thats why some times skinny people have six pack abs because they do not have fat on their stomach. keep doing your other work out especially the ab crunches. I am a skinny guy so I do not do cardio at all at the gym i just do lifting for all my major muscle groups. I am trying to gain 20 lbs.
How else would you get a six pack…
There is a genetic component to it.
Okay, NO ab exercises alone wont burn the fat from your stomach. You have to do those exercises, while also doing intense cardio 3 times a week minimum. Since your building the ab muscles, when you do cardio the ab muscles will slowly start to burn the fat around your stomach, as do all yoru muscles in your body when they burn the fat in legs arms and so forth.
so start running and doing the exercises and you will see results
doing those exercises will develop the muscle but for it to show you have to burn the fat, so do all the exercises that you do then run.
Diet and exercise are the best ways. If you want to avoid cardio, continue weight lifting but do higher reps and super-set. Cardio would definitely help though.
Doing ab excersizes isn’t going to get rid of only belly fat – fat doesn’t localize like that.
Fat will disappear evenly all over your body as you lose it. Which is what you want, but don’t concentrate solely on upper body – put the whole body to work with cardio to burn fat overall, then do the resistance/weight/crunch training to get the abs to pop.