Prior to a petition being filed under this chapter, the designator may revoke the appointment of a standby or temporary custodian by destruction of the designation and notification of the revocation to the standby or temporary custodian.
After a petition has been filed, the designator may revoke the designation of standby or temporary custodian by:
(1) executing a written revocation;
(2) filing the revocation with the court; and
(3) notifying the persons named in the designation of the revocation in writing.
An unwritten revocation of the designation may be considered by the court if it can be proven by clear and convincing evidence.