Remove "black" from text boxes on pdf / word documents

17 documents each 20 - 40 pages long. Currently PDF format. Wherever these documents have been redacted they have a black text box with yellow or white writing, sometimes quite large, which will consume ink and be clumsy to print. I need someone with good macro skills simply to convert the black infill in each box to white. You are welcome to transfer the documents to word if that is easier. Nothing else in content or layout is to be altered.