PyMuPDF to the rescue…
Code:
#https://artifex.com/blog/advanced-text-manipulation-using-pymupdf
import fitz
doc = fitz.open("original.pdf")
page = doc[18]
#print(page.get_text())
rect = fitz.Rect(0,0,424,50)
page.add_redact_annot(rect)
page.apply_redactions()
doc.save("redacted.pdf")
#ebook-convert.exe redacted.pdf redacted.epub
Hard to believe no ready-to-use command-line tool can add and delete redaction annotations.
Another useful tool would be a PDF viewer that lets the user select a rectangle and display its coordinates, ready to be copy-pasted into the command line.