Você pode usar bindParam ou bindValue antes de tentar executar a consulta.
$command = " DELETE FROM SoccerPoll WHERE Id=:id LIMIT 1";
$stmt = $dbh ->prepare($command);
$stmt->bindParam(':id', $_GET['Id'], PDO::PARAM_INT);
$stmt->execute();
$command = " DELETE FROM SoccerPoll WHERE Id=:id LIMIT 1";
$stmt = $dbh ->prepare($command);
$stmt->bindParam(':id', $_GET['Id'], PDO::PARAM_INT);
$stmt->execute();
