How could his father agree to his renunciation?

Having found out what his son had in mind, King Suddhodana tried many ways to detain him, especially by surrounding him with worldly pleasures. When Siddhattha was only 16 years old, King Suddhodana arranged for him to marry Princess Yasodhara from a neighboring state. Yasodhara bore him a son name Rahula. But all this was in vain. He finally slipped out of the capital city in the still of a night. He entered a forest, took off his princely clothes and, having shaven his head and beard, became a wandering mendicant. Regarding his age at the time of renunciation, there are two different accounts—one says nineteen, and the other twenty-nine.