Unless stated otherwise, a destroyed vehicle should be marked with some cotton wool smoke and left on the table. It is then treated as difficult terrain for the remainder of the battle. Other vehicles may not move over it but can push the wreck aside if their frontal Armour value is higher than that of the wreck. If the vehicle doing the pushing has a dozer blade or rough terrain modification (or some other device, we detail as having this ability in the future) they may move vehicles with an equal frontal Armour value.
Wrecks
Source: 3rd-A-Palooza (3.5) Rulebook v1.4, p. 41