How to delete an iBook from your iPad library
You can delete iBooks from your collection using the following steps:
1) Tap iBook on your iPad homescreen.
2) Tap “Edit” in the right hand corner of your iBook bookshelf. You will now see on the top right hand screen two new buttons appear. They are the “Move” button and a red “Delete” button.
3) Now select the books you want to delete by touching them. You will see the books highlighted in white. (Many describe the icon as losing few shades of color.) Tap on all the books you want to delete. If you accidently touch a book you do not want to delete, just tap it again deselect the icon.
4) Tap red “Delete” button on the upper left hand corner and confirm delete.
5) You will now have to sync your iPad to make the deletions permanent. Open iTunes on your computer and connect your iPad to your computer.
6) In the Books tab, turn off the checkbox next to the unwatned title and click Apply or Sync. The benefit of doing it this way is your book is left in your iTunes archive but kept off your iPad.
Note: Not only can you delete books with the method described above, you can also rearrange the books essentially doing the same process. Just select the books you want and press “move” instead of delete.