You can block out text (black out), or erase it (white out) with the redact function.
You will not be able to redact text that has already been made editable using the Correct Text button . That text can instead be deleted. (Editing and Correcting Text).
Redact a rectangular area of your document.
All of the content in the rectangle area is securely redacted.
From a search, you can redact keywords and phrases. (Searching PDFs).
Note: If there is any sensitive information in the document metadata, you must remove it manually in the Inspector under the Document Information tab (Command+Option+5). Find-and-Redact and Find-and-Replace do not scan the metadata.