Indiana Code Title 16. Health § 16-36-7-32

Sec. 32. (a) The declarant who signs an advance directive may revoke that advance directive by any of the following:

However, if a declarant has not been determined to be incapacitated under section 35 of this chapter, the declarant always has the right to orally revoke a health care decision that is included within an advance directive under section 28(a)(2) of this chapter or a statement of desires or treatment preferences that is included within an advance directive under section 28(a)(3) of this chapter, despite any contrary wording in the advance directive.

(b) Until a health care representative or health care provider has actual knowledge of a valid revocation of an advance directive:

(c) A declarant who has signed a valid advance directive may amend or restate that advance directive in a writing that is signed in compliance with section 28 of this chapter and witnessed or acknowledged in compliance with section 28(c), 28(d), or 28(e) of this chapter.  The amendment or restatement may take any action that could have been included in the former or original advance directive.