The Destroyer is a gadget that, when triggered, removes the object that has the Destroyer gadget on it. This feature was introduced in LittleBigPlanet 2 alongside with the other logic. The Destroyer object can also destroy objects glued to the object that is placed on. However, you can change the settings to only destroy that object or destroy glued objects in that area too! You can also even change the visual effects of how the destruction looks.
In conjunction with the Threshold gadget in LittleBigPlanet Karting, you can use the Destroyer and another gadget to destroy bits of the track so players can go through it (if there is a branch or a breadcrumb in it).