Alberto says: In the Roman rite of the Catholic Church, once a man or woman has made solemn, perpetual religious vows, the process of release from these monastic vows is not a simple one. It is not approved simply by the individual monastery, but requires the approval of the ecclesiastical authorities.
Normally there is a transitional period, called exclaustration, in which the person looks to establish a new life and determine if this is what he or she is truly called to do. This usually lasts up to six years under the current Code of Canon Law.
After this period, the appropriate authority — either the local bishop, or, more normally, the Holy See — normally determines that the wish to leave this life is valid and grants the former monk or nun release from their vows.