In response to questions sent by PM, I recorded a video showing the steps outlined above:
Screencast video:
http://www.youtube.com/watch?v=ynrPB9rAOhc
The document shown in the video is attached below. Note that it has a short page size so that an entire page will fit on the screen.
The steps shown in the video are described here:
1) Format > Styles and Formatting
Footnotes created in Writer automatically use the "Footnote" paragraph style. Any change to this style will automatically apply to all footnotes in the document.
2) Right-click on the "Footnote" style name in the list and choose "Modify".
3) On the "Font Effects" tab, choose option Hidden: YES (toggle the check by clicking on the box)
4) Click OK.
This will hide all the footnotes in the document, but the footnote anchors are still shown.
5) Switch to view the list of character styles; select "Footnote anchor," then right-click and "Modify". Choosing option "Hidden" again would be logical, but it does not work for some reason[*].
Instead, change the font color to white to make the footnote anchors invisible. You could also change the font size to something small to reduce the size, if you want.
The footnote separator is still visible. To hide the separator, modify the page style(s):
6) Format > Page > Footnote > Separator line > Length: 0%
The notes are not lost, only hidden, and you can bring them back by simply reversing the above steps at any time.
Contrary to what I wrote above, and to how Writer handles other hidden text, you
can't toggle the hidden footnotes using View > Nonprinting characters.
[*] This is a known bug:
Issue 38303:
Footnote anchors cannot be hidden via character style
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