Idaho Code § 15-5-203
A minor of fourteen (14) or more years may prevent an appointment of his testamentary guardian from becoming effective, or may cause a previously accepted appointment to terminate, by filing with the court in which the will is probated a written objection to the appointment before it is accepted or within thirty (30) days after notice of its acceptance. An objection may be withdrawn. In the event of such objection, the alternate guardian next in priority named in the will may accept appointment as set forth in section 15-5-202, Idaho Code, and the minor shall have the same right of objection. An objection does not preclude appointment by the court in a proper proceeding of the testamentary nominee, or any other suitable person.
Idaho Code § 15-5-203