To remove a page from your book, click on the page so that the preview image of it appears above the page navigator. Once you see the image, above it you will see a trashcan icon. Clicking on this icon will remove the page from your book.
If you wish to remove a recipe entirely from your account, you must first make sure that the recipe does not appear in any of your books. Locate the recipe in your recipe box and hover over the title. To the left of the recipe, you will see a pencil icon which you need to click on to bring up the edit recipe pop-up. Once the pop-up has appeared, there will be a delete recipe in the bottom left hand corner. If the button is grayed out, then the recipe still appears in a book and must be removed. If the button is not, then you can click on this button to remove the page from your account.
To delete multiple pages, click on the Arrange Pages button. You can delete multiple pages using this interface. There are two ways to select multiple page depending on how the pages are situated. If all of the pages are consecutive, then you can click on the first page, hold down the SHIFT key, and then select the last page in the series. You'll notice that both those pages, along with all of the pages in between will be highlighted. To select pages that are not consecutive, you will click on each page individually while holding down the Control key.
Once the pages you want to delete are highlighted, click on the Delete Pages button in the top right hand corner.