Sometimes during combat, Trico will knock down the suit of armor enemies and they will not instantly die. They will usually stay on the floor for a few seconds before getting back up when this happens. While they are on the floor, walk up the them, hold Circle, and press the Left Analog-stick near their head to pull off their heads. Do this ten times to get the "Losing Their Minds" trophy. A great farming spot to do this is at the end of the game, on your way up the last tower, where you will have the two largest enemy encounters in the game. There are some stronger suits of armor (white armor) that can take up to three hits from Trico. Wait for one of them to get knocked on the ground and quickly pull off their head. Then, restart the checkpoint before the battle ends and repeat the process until you get the trophy. The game creates an automatic checkpoint after the fight. It can also be done over multiple playthroughs, as your progress carries over into New Game+.