GHOST 1.0

It's easier if you do this on New Game + but if you wanna try doing first time, Save and Quit before entering the room. You can use items like Killer Drone and Red Wrath to increase your damage, maybe you have Vertical Laser to help. If you can't kill it in time, exit game, reload then try again or go farming energy cubes to buy powerups and items or go trigger some alarms if you're on survival for those items. In the next zone after the biped, you'll get a very powerful primary weapon that will make this achievement a breeze but you can use it on him at New Game +. If you can't do this right now, next time you will for sure.