I want to delete books on my kindle app on ipad. When I try up comes download or add to collection. Delete will not come up.HELP

If you want to permanently delete them you need to access Amazon's website: Amazon.com > Kindle Store > Manage Your Content and Devices > [select book] Actions > Delete from Library. You will then be prompted: Are you sure you want to permanently delete this title? Doing so will permanently remove this title from your account, and you will have to re-purchase it if you want to read it again.