[-Prodigy-]

pawn Code:

new vehToDelete[MAX_VEHICLES] = {-1, ...};

// in your cmd
vehToDelete[vehicle] = CreateVehicle(...)

CMD:deletevehicles(playerid, params[])
{
    for(new i = 0; i < MAX_VEHICLES; i++)
    {
        if(vehToDelete[i] != -1)
            DestroyVehicle(i);
    }
    return 1;
}