Select Design > Watermark. (In Word 2010 or 2007, select Page Layout > Watermark.)
Select Remove Watermark.
If you can't delete a watermark using Remove Watermark, try this:
Double-click near the top of the page to open the header area.
Put your cursor over the watermark until you see a 4-way arrow.
Select the watermark.
Press the Delete key on your keyboard.
Repeat as necessary to remove all watermarks.