The product that you have in your database, is in category 1, not category 6 which is where the link attached to your image points to.

What you refer to as a page is not really a page at all, but Zen Cart's attempt to build a page when your template sends it somewhere that doesn't exist. So you can't turn the page off - because it doesn't exist to start with. All you can do is make it exist by putting a product in the category pointed to, or turn of the link to it by tracking it down using the advice given above.