You can only remove by voting if he has come to power by voting - in the case of MMS he is not elected but a selected PM. He has never fought any election and won, he is member of Rajya Sabha and has been chosen by Congress president Sonia Maino to be PM - that's why we see irrationality and lack of accountability in his decisions. He is not a leader but a buracrate who knows to obey commands of his political masters - in his case it is her Madam Sonia Maino.
