Q: How do I hide deleted ibooks

To hide it from the cloud you need to use your computer's iTunes (iBooks app is using an up-to-date Mac) : Hide and unhide purchases in the iTunes Store - Apple Support

(You should be able to turn off the showing of icloud books directly in the iBooks app on your iPad, tap the collection name at the top middle of the bookshelf and at the bottom of the list of collections there should be a 'hide iCloud Books' on/off button.)