If your blog is public and does offer subscriptions then that's not possible. You hcan make the blog visibility "private" but yu cannot delete a subscriber from a public blog, and you cannot block anyone from subscribing to a blog that has a "public" setting. What's critical is not who reads the blog. Every WordPress blog has built in RSS feeds for mboth posts and fro comments and anyone can use a feedreader to read your posts. As the blog is "public" and you offer email subscriptions any member of the public can subscribe. However, you can control which comments are moderated, approved and appear on your blog. http://en.support.wordpress.com/unwanted-comments/ No one can drive you crazy if you do not allow them to do so. Simply ignore the comments rather than approving them and posting them.