It should be easy, and it's not clear from your description why it doesn't work. Of course, the text is plain text, and the page number is a field, so the details are different, but still it should be easy.
Can you insert a page number in another (new) document and delete it again? That shows (a) that it can be done in principle, and (b) how to do it.
The work-around would be to set the font of the page footing style to color white. It's printed then, but you don't see it.
Kees
I've tried just about everything and am about to rip my hair out. Am working with a Word 2003 document, I copied and pasted a few pages from another Word document which contained a footer that identified my organization and the page number. I was able to delete (from the footer) the text, but Word won't let me delete the page number. To make matters worse, the page number is appearing on all of my pages! I've tried deleting the offending data from the footer on many different pages, no luck. Help!

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic