Order (Ex): (...) A samurai who wishes to change his order must undertake a lengthy process to dedicate himself to a new cause. When this choice is made, he immediately loses all of the benefits from his old order. He must then follow the edicts of his new order for one entire level without gaining any benefits from that order. Once he has accomplished this, he gains all the bonuses from his new order. The only exception to this is when a samurai decides to become a ronin. A samurai can elect to become a ronin immediately, losing all the benefits from his old order and replacing them with the new benefits from the ronin order. Once a ronin, however, the only way for the samurai to change to another order is through the method described above. Note that the names of these orders might vary depending upon the campaign setting or GM’s preference. (...)
Becoming a Ronin: Normally, when a samurai wishes to change his order, he must undergo a lengthy process that requires him to adhere to the edicts of his new order for a period of time before receiving any benefits. This is not the case with ronin. Once a samurai decides to become a ronin, he immediately loses all of the bonuses, skills, and abilities of his old order and gains those of the ronin order. If he wishes to once again dedicate himself to another order, he must do so using the normal rules.
Edicts: Ronin follow their own personal code of ethics and honor. As such, their edicts are extremely flexible and subject to change. Each ronin should determine his own edicts, which should include at least three provisions. These edicts are subject to GM approval.
If a ronin wishes to change his edicts, but wishes to remain a ronin, does it require just the approval of GM, or something more?
Due to being fluff, it's subject to DM approval. If the character has changed alignment due to a conversion of faith, for example, his previous edicts may not apply. Treat this as similar to a Paladin's code, with all the tangled RAW that entails.
A player should be able to strongly justify why their character would change their edicts, and typically it should be a conscious decision they've made after serious internal reflection, and not in response to a sudden sticky situation their character has found themselves in to try and weasel out of their edicts.