Remove "Preview" button from Custom Post type edit page

gistfile1.php

// Hide "Preview" button
function hide_preview_button()
{
    global $current_screen;
    if ( 'CUSTOM_POST_TYPE' == $current_screen->post_type ) {
          echo '<style>#preview-action,.updated a{display:none;}</style>';
        }
}
add_action('admin_head', 'hide_preview_button');

Remove the view buttons on the custom post type list, as well as the slug (which can be clicked to access the view) from the custom post type page:
<style>#preview-action, .updated a, #edit-slug-box, #the-list .row-actions .view {display: none;}</style>