I'm not familiar with the details of why the great saint got disinherited

And now his father according to the flesh, having despoiled him of his money, brought this son (no longer his, but the child of divine grace) before the Bishop of Assisi, to compel him to renounce in his hands all his inheritance, and whatsoever he had received from him, which this true lover of poverty was most ready and willing to do. As soon, therefore, as he came into the Bishop’s presence, without a moment’s delay, neither waiting for his father’s demand nor uttering a word himself, he laid aside all his clothes, and gave them back to his father. Then it was seen, that under his fair and costly garments the holy man wore a hard and rough hair-shirt. With marvellous fervor he then turned to his father, and spoke thus to him in the presence of all: “Until this hour I have called thee my father on earth; from henceforth, I may say confidently, my Father Who art in Heaven, in Whose hands I have laid up all my treasures, all my trust, and all my hope.”