How do I black out or cover up sensitive information "AFTER DOCUMENT IS SIGNED"

I have a scenario where I need some very specific clarification.

We have clients fill out a form and sign it. We then take the information and enter it into our online software we use, which encrypts sensitive data. After we enter the information in, we need to be able to black out small portions of sensitive data in the document to remain compliant. We cannot have that information exist.

With that, my questions are:

After a document is signed, does that storage of that document with Adobe remain PCI compliant? PCI compliance states that if the information is viewable after it is entered, it is not compliant. (I need this specifically addressed by someone at Adobe--not just shown a copy and pasted PCI compliance seal of approval).

How can we redact or black out that information after it has been signed? We need to make the original no longer exist and only the redacted version exist.