A redaction is a special kind of annotation used to hide confidential information on an image document. A redaction is a permanent black or white rectangle that obscures an area of the document.
Redactions can be created and saved on image documents whose Document Types are configured to allow redactions. See your system administrator to verify whether a Document Type has been configured for redactions.
A redaction cannot be deleted (or undone) once it has been saved. When a redaction is saved, the redacted document is stored either as a new document in another Document Type or as a revision of the current document. How the redacted document is stored depends on your system's configuration.