直接上代码，比较简单

<?php
/**
 * 在文章提交框中添加“移动至回收站并通知作者”
 */
add_action( 'post_submitbox_misc_actions', 'ttzip_delete_notice_metabox' );

function ttzip_delete_notice_metabox() {
    global $post;

    if ( ! $post instanceof WP_Post ) {
        return;
    }

    $nonce = wp_create_nonce( 'ttzip_delete_notice' );
    ?>
    <div class="misc-pub-section">
        <a href="javascript:void(0);"
           class="submitdelete ttzip-delete-notice modown-delete-notice"
           data-id="<?php echo esc_attr( $post->ID ); ?>"
           data-nonce="<?php echo esc_attr( $nonce ); ?>">
            移动至回收站并通知作者
        </a>
    </div>

    <script>
    jQuery(function($) {
        $(document).on('click', '.ttzip-delete-notice', function(e) {
            e.preventDefault();

            var $link = $(this);
            var ret   = prompt("删除理由", "");

            if ( ret === null ) {
                return;
            }

            ret = $.trim(ret);

            if ( ret === "" ) {
                return;
            }

            $.ajax({
                url: ajaxurl,
                data: {
                    pid: $link.data("id"),
                    why: ret,
                    nonce: $link.data("nonce"),
                    action: "ttzip_delete_notice"
                },
                dataType: "json",
                type: "POST",
                success: function(t) {
                    if ( t.status == 1 ) {
                        location.href = "/wp-admin/edit.php";
                    } else {
                        alert(t.msg);
                    }
                },
                error: function(XMLHttpRequest, textStatus, errorThrown) {
                    alert("请求失败，请重试");
                }
            });
        });
    });
    </script>
    <?php
}

add_action( 'wp_ajax_ttzip_delete_notice', 'ttzip_delete_notice_callback' );

function ttzip_delete_notice_callback() {
    date_default_timezone_set( 'Asia/Shanghai' );

    $status = 0;
    $msg    = '处理失败';

    // 验证 nonce
    if ( ! check_ajax_referer( 'ttzip_delete_notice', 'nonce', false ) ) {
        wp_send_json( array(
            'status' => $status,
            'msg'    => '安全校验失败'
        ) );
    }

    $post_id = isset( $_POST['pid'] ) ? absint( $_POST['pid'] ) : 0;
    $why     = isset( $_POST['why'] ) ? sanitize_text_field( wp_unslash( $_POST['why'] ) ) : '';

    if ( ! $post_id || ! $why ) {
        wp_send_json( array(
            'status' => $status,
            'msg'    => '参数不完整'
        ) );
    }

    $cpost = get_post( $post_id );

    if ( ! $cpost ) {
        wp_send_json( array(
            'status' => $status,
            'msg'    => '文章不存在'
        ) );
    }

    // 只有管理员可以操作
    if ( current_user_can( 'administrator' ) ) {

        // 如果 _mbt_add_notice 存在，则发送通知
        if ( function_exists( '_mbt_add_notice' ) ) {
            _mbt_add_notice(
                $cpost->post_author,
                sprintf(
                    __( '您好，您发表的文章《%s》审核不通过，原因：%s。', 'ttzip' ),
                    $cpost->post_title,
                    $why
                ),
                'post_trash',
                $post_id
            );
        }

        wp_trash_post( $post_id );

        $status = 1;
        $msg    = '已移动至回收站并通知作者';
    } else {
        $msg = '权限不足';
    }

    wp_send_json( array(
        'status' => $status,
        'msg'    => $msg
    ) );
}