Frequently Asked Question:
Redact information from a PDF
Can Quick PDF Library be used to redact information from a PDF?
No, Quick PDF Library does not include any redaction features at the moment.
While it's possible to hide text or images or even other information in a PDF file using Quick PDF Library, it is not possible to permanently delete certain objects without leaving some sort of trace. Proper redaction is quite difficult and we that if you have sensitive information that you need to remove from a PDF file, then using the latest versions of Acrobat is a good place to start.
There are some other options, such as using the DrawBox function to draw a rectangle over some text or images and then filling that rectangle with a different color and then rendering the PDF to an image and then converting it back to a PDF -- but this is really a brute force method and will leave you with a PDF file that does not contain any text, just one big image.