Select the Redact tool and drag a rectangle over the content you want removed. Seben removes the page text and images under the box, rather than covering them, and puts a black box in their place. It then checks the result by re-extracting the text.
Redacting creates a new version of the document. Earlier versions keep the original, so anyone in your workspace can still restore it: File → Version history… lists every version. If you redact something by mistake, restore the earlier one.
To share a redacted document, download the redacted version: File → Download while it is the current version.
You can also ask the agent, for example “Redact all emails”. In Ask mode, the default, it waits for your approval before it redacts anything.