I found a really easy way to do this, and not too far into the game.
After you unlock the "evasive kick" skill & the "push" ability
find a stormtrooper close to an edge. Press
to kick him, then
to push him off the edge. Even though he dies from the fall, the game still counts it, and achievement unlocks. FYI I popped it by the stormtrooper hitting the ground, so not 100% sure if it works if they fall into an abyss, or if it works on animals. Anyone who can confirm either way, I'll credit in an update.