Change 1000+ of WordPress Featured Images in 5 Minutes! › Forums › Questions and Answers › Remove First Image & Delete from Library › Reply To: Remove First Image & Delete from Library
In tests on my local computer the removal of the image works with the code of the page you provided via email. It is difficult to look for an answer without not knowing your WP installation. There could be very simple reasons like you do not have rights to edit that post, or there could be complex reasons because of a special configuration of the site.
May I take a look at the backend of your site? If yes please mail me the login credentials.