A redaction box hides content visually. On its own it does not remove the text underneath, which stays extractable by anyone who copies from the file.
To actually remove it, this editor rebuilds each redacted page as an image when you save. That page's text stops being selectable and any form fields on it become static. Pages you did not redact are untouched.
Pick one to place, or draw another. They are kept in this browser, as lines rather than pictures, so they stay sharp at any size.
Nothing saved yet.
Draw in the box. The line under it is a guide, not part of what is saved.
A PDF stores glyphs with coordinates, not paragraphs. Converting means working out where the paragraphs were, so the result is a rebuilt document that reads the same rather than a copy that looks the same.