The latest PDFPenPro, and Adobe Acrobat Pro can truly redact text, graphics, or regions of both. This redaction is not an overlayed color, but true redaction that cannot be searched, or undone in a PDFEditor once the original content is redacted. PDFPenPro has a free trial on their website, and it is north of $100USD.
I tested the redaction by using a custom PDF search tool that I wrote, and opening the redacted PDF in Preview, and Acrobat Reader DC. No search was successful for the original content prior to its redaction.
Another tool that can open and edit PDF text is Affinity Designer. It does not do redaction. OS X App Store, and web site has free trial.
I get no compensation, or consideration for any product mentioned in this reply.