How do I delete books I've already read on my IPad in my Kindle app?

You need to log in the same kindle account and the purchased books will be synced automatically. If this doesn't work, you can convert the kindle books to epub file and transfer to ipad. You need to connect your Kindle device to computer and then convert the books in Kindle. After that, you can transfer the books to ipad with iTunes or iTransfer. For more details, check: A Simple Guide to Help You Read Kindle Books on iPad

How to Delete Books from Kindle on iPhone iPad Plus Kindle Devices the...

If you want to get free eBook for Kindle , there are many webistes for you to download. but when you find that you cant read the book smoothly, it may because of the DRM-protection on the book, Check this guide How Do Share Kindle Books on iPad

In general, you just need to log in Kindle account on your iPad and your purchased book will be synced automatically. However, if you don't want to log in your account. You can convert the kindle books to epub file and read on iPad directly. Just follow this guide.

A Simple Guide to Help You Read Kindle Books on iPad

If you have piles of books in your iPad, you may want to delete books from iPad to free up iPad storage space. The easiest way to do that is deleting books in iBooks app. You need to go to iBooks app, and tap Select at the upper right corner. Then select the books you don't need and tap Delete at the upper left corner.


If you have many ebooks to delete, deleting books in iBooks app may be a little complicated. So you can re-sync iPad with iTunes to delete books from iPad. This is also is easy to be done, and you only need to connect your iPad to computer with USB cable, and sync iTunes Books library with iPad. After that, you'l get the books from iTunes library to iPad.

Get more information here.
http://www.leawo.org/tutorial/how-to-delete-books-from-ipad.html

How to Install the Kindle App for iPad/iPhone The Kindle app can be used on any iPad, iPhone, or iPod touch with iOS 3.2 or greater installed. Installing the Kindle App Visit the App Store and download the Kindle app to start reading from your iPad, iPhone, or iPod touch. To install the Kindle app: 1. Tap the App Store icon on the home screen of your iPad, iPhone or iPod touch. You can also get the app through the iTunes Store. 2. Search for "Kindle" or find it in the alphabetical list of apps. 3. Follow the on-screen installation instructions. When installation is complete, tap the Kindle icon on your device to open the reading app. Registering the Kindle App To register your Kindle app, use your existing Amazon account e-mail address and password. If you live outside the United States and use the Kindle application, please see the Using the Kindle App if You Live Outside the United States Help page. Logging into your Amazon.com account through the Kindle app registers your device to your Amazon.com account. Once you sign in during registration, you won't need to do it again -- just open the app to access your Kindle Library. To register: 1. Tap the Kindle icon on your iPad, iPhone or iPod touch to open the reading app. 2. Enter your Amazon.com account e-mail address and password. 3. Tap the "Register" button. You can also tap the Settings icon (the cog) on the Kindle Home screen to view or change your account registration. Signing Out and Deregistering If you sign out of the Kindle app, your reading app is deregistered from your Amazon.com account. When you deregister, you can't download content to the Kindle app or send purchases to the app unless you register again. To deregister using the Kindle app: 1. Tap the Kindle icon on your iPad, iPhone or iPod touch. 2. Tap the Settings icon in the lower right-hand corner of the screen. 3. Tap "Update" under the Registration field and then tap the Deregister button. To deregister online: 1. Visit Manage Your Kindle on Amazon.com. 2. Open the Manage Your Devices section and locate your registered Kindle app. 3. Click the "Deregister" link. http://www.amazon.com/gp/help/customer/display.html/ref=hp_ipst_inst?nodeId=200438220&# installing

Simple enough. Just delete the Kindle App from your iPad, go to the App Store and download the Kindle App again. It should work fine after that!

Simply access the Kindle library on your iPad (last screenshot here: http://iphoneappbackup.wordpress.com/2014/06/23/how-to-read-kindle-books-on-ipad/) and delete the books of your choice from there.

Hey , three steps are enough
Step1: Open the Kindle app on your iPhone
Step2: Tap and hold the book you need to delete.
Step3: Tap the pop-up "Remove from device" to remove the book.
more ways to remove books permanently. check this guide out!
How to Delete Kindle Books from iPad or Kindle Cloud

If you've already tried deleting the book on the kindle itself, have you tried plugging in the kindle (to your computer), navigating to the Documents folder inside and deleting the actual book file?