CMD:dveh(playerid, params[])
{
    new playerState = GetPlayerState(playerid);
    if(PlayerInfo[playerid][Padmin] >=2)
    {
        new currentveh;
        currentveh = GetPlayerVehicleID(playerid);
        DestroyVehicle(currentveh);
    }
    else if(PlayerInfo[playerid][Padmin] <=1)
    {
        SendClientMessage(playerid, -1, "Your not high enough level to do that");
    }
    else if (playerState == PLAYER_STATE_ONFOOT)// all of this
    {
        if(PlayerInfo[playerid][Padmin] >=2)// doesnt show this
        SendClientMessage(playerid, -1, "You need to be in a car to use this command");// or this
    }
    return 1;
}

CMD:dveh(playerid)
{
      if(PlayerInfo[playerid][Padmin] < 2) return SendClientMessage(playerid, -1, "Your not high enough level to do that");
      if(!IsPlayerInAnyVehicle(playerid)) return SendClientMessage(playerid, -1, "You need to be in a car to use this command");
      new currentveh;
      currentveh = GetPlayerVehicleID(playerid);
      DestroyVehicle(currentveh);
      return 1;
}

native IsValidVehicle(vehicleid);

// snippet of my /dveh command.
if(!IsValidVehicle(targetveh))
        return SendClientMessage(playerid, COLOR, "Vehicle doesn't exist.");