Photographers can opt-out of offering their images as prints. You can review your settings and opt-out of prints on the Prints section of your Account Settings here. Depending on the size of your portfolio this setting can take up to one business day to update on all your images.
Picfair only offers the ability to opt-in your entire portfolio for wall art, or opt-out altogether. Offering this kind of fine control where you can opt images into print products on an image by image basis is something we are looking at for the future.