Neb. Rev. Stat. § 30-4627

A powerholder of a releasable power of appointment may release the power in whole or in part: (1) by substantial compliance with a method provided in the terms of the instrument creating the power; or (2) if the terms of the instrument creating the power do not provide a method or the method provided in the terms of the instrument is not expressly made exclusive, by a record manifesting the powerholder's intent by clear and convincing evidence.