Deleting Bookmarks and History in iPad
As long as the iPad is not synced with other devices which might be adding those websites in history or website data again, these steps might help.

Tap on the "open-book" type icon in Safari to reveal bookmarks tap edit to remove them.

If you can delete your history, do it!

Go to Settings-> Safari-> Clear History and website data. 

Make sure that the item is not in the Reading List either.