Word doesnot "see" pages, only paginates as per default printer and page
break commands.
There are several ways of doing what you want, firstly save the document as
a new document (just in case), go to the start of page you want to keep,
Ctrl+Shft+Home, this will select all that is above your page, delete, goto
the end of the page your want to keep, Ctrl+Shft+End, to select the rest of
the document, delete, save.
Or you can use the GoTo function, have the cursor on the page you wish to
keep, GoTo (Ctrl+G), type \page in the Enter Page Numebr box, OK. This will
select all that is on this page, then you can copy/paste into new document.
For further infomation on "Word Doesn't Know What a Page Is" see:
http://daiya.mvps.org/wordpages.htm
Hope this helps
DeanH