The first robot is destroyed when the group lures it into an elevator and then blows the cables with some propane tanks that were earlier placed near them, causing the elevator to drop all the way to the bottom and explode on impact.
The second one is destroyed when Ferdy (Tony O’Dell) and Rick (Russell Todd) set up some mirrors and make it shoot its lasers at them, and the lasers bounce back and hit the robot, short-circuiting it until it blows up.
The last one is destroyed when Alison (Kelli Maroney) goes into a paint shop and smears paint all over the floor, then lures the robot inside and sets the paint off with a flare, blowing up both the store and the robot.
Ferdy and Alison are the only survivors.
Thanks Tornado Dragon!