Go back and click "revise" on your listing. When the page comes up, where you have your set price, it will also either have "allow offers" OR click on "other options" ... you will THEN see "allow offers" ... just untick the box and it will be gone ... 'tho Ebay seem to randomly do this and allow offers on listings, I've had to rectify mine quite a lot, as I know others have too.
