How to redact a PDF without Adobe(and actually remove the text)
You don't need Adobe Acrobat to redact a PDF. Acrobat Pro is a paid subscription, and most of the time you just want to black out a few names or numbers before sending a file. The part that matters is whether the redaction actually deletes the text underneath or only hides it, because a lot of free methods only hide it.
Method 1: Redact it in your browser
This is the one I'd use. Open the free tool, drop in your PDF, and draw a box over anything sensitive: names, account numbers, signatures, dates of birth. When you apply it, the text and images inside each box are deleted from the file and the page is flattened, so there's nothing left to copy out. The file stays on your device the whole time, and manual redaction is free.
Method 2: Use Preview on a Mac
Every Mac has Preview, and recent versions have a proper Redact option in the Tools menu or the markup toolbar. Pick it, select the text, apply, save. The catch: older versions of Preview only drew a filled rectangle, which is not redaction. If all you can find is a shape tool, treat the result as "hidden" and verify it before sending.
Method 3: Delete it in Word, then export
If you still have the original Word document, delete the sensitive text there (actually delete it, don't highlight it black), then save as PDF. The text never makes it into the PDF in the first place. This only helps when you own the editable source, and you'll want to clear tracked changes and comments so nothing is retained.
Check that it worked
Whichever method you used, open the finished PDF, select all the text, copy it, and paste it somewhere plain. If a redacted value comes back, the tool only covered it and you need to redo it properly. If you want the longer explanation of why covered text is so easy to recover, here it is.
For the free route, a browser tool that burns the redaction in gets you a permanent result without paying for Acrobat or uploading your file anywhere.