Due to the Battle of New York, Tony Stark suffered from anxiety and built dozens of Iron Man suits in an attempt to reassure himself. However, he also designed the Clean Slate Protocol as a means to instantly command the destruction of all these suits if need be.
Following the Battle on the Norco, Stark resolved to spend more time with his girlfriend Pepper Potts, who had nearly died during the battle. Therefore, Stark ordered J.A.R.V.I.S. to enact the Clean Slate Protocol, triggering the destruction of the whole Iron Legion. As a result, all the suits exploded, creating a home-made Christmas firework show over the Norco.