Hi LoganSaj,
Select your insertion point, then:
. press Ctrl-F9 twice, to create a pair of nested field braces - they'll look like '{ { } }'
. fill in/around the field braces so that you end up with '{={NUMWORDS}-1}'
. select the field and press F9 twice.
In theory, a NUMWORDS field alone (ie {NUMWORDS}) should suffice but what happens in practice is that, after the first update, the NUMWORDS field includes itself in the count.
Note: The count returned by a NUMWORDS field will not include page headers, page footers, footnotes or endnotes, but it will the include footnote & endnote reference numbers. Hidden text is only counted if your print options are set to print hidden text.