You'll have several opportunities for this achievement throughout the game, but I found doing this in Asgard to be the easiest. This particular Frost Goliath has some moves that will help you, and he also doesn't regenerate armor like the later ones can. Most of the way through the world a Frost Goliath will appear. You can kill him one of two ways. You can damage him until his life bar is depleted, or you can damage him until grapple points appear on him. Grapple him and destroy his armor and pull the Jotun out of the Goliath, which is faster.
The Frost Goliath in the first world will have some moves that will make this achievement easier. If you stay away from him, he'll do a couple different ranged projectile attacks, but then he'll also do a ramming attack. If you dodge the ramming attack, he'll crash and automatically be stunned with grapple points available to you. Just stay away from him, dodging his projectiles until he rams, dodge that, then grapple and destroy a part of him. Rinse and repeat until he's dead. You can quit and continue if you get hit and you'll be right back at this point.