You can’t. You can only unpublish it, which means that the book will no longer be available for purchase.

To delete books from your Kindle, go to the “Home” screen and select “Archived Items.” This will bring up all of the content you’ve archived on your Kindle. Select the title you want to delete, then press the button that says “Remove from Device.” You can also remove content by opening it in the Kindle app on your phone or computer and tapping the three dots in the top right corner.

KDP Select lasts for 90 days.KDP Select lasts for 90 days.

Since the book is enrolled in KDP Select, it will be unavailable for purchase on other platforms.