In Mahmud's view, the destruction of the Janissaries was necessary to restore stability to the Ottoman throne. In an event which would later come to be known as 'the auspicious incident' on the 15th June 1826, Mahmud brought his ordinance into effect and disbanded the Janissaries. They did have enough power to overthrow the Sultan and the only way to do this was if everyone agreed on it.
C. They were plotting to overthrow the sultan