§1. After having considered the matter seriously before the Lord, a perpetually incorporated member who wishes to leave the institute is to seek an indult of departure from the Apostolic See through the supreme moderator if the institute is of pontifical right; otherwise the member may also seek it from the diocesan bishop, as it is defined in the constitutions.
§2. If it concerns a cleric incardinated in the institute, the prescript of can. 693 is to be observed.
Source: Code of Canon Law (Vatican.va)