We took a look at the whole situation and we can confidently say that those 'Related Articles' under your recent posts are not ours, which is why you can delete our plugin from your FTP server.
But this doesn't make our situation any less weirder! That redirection when clicking on the Activate, Edit or Delete button is something we cannot get to the bottom of. Sorry!
But I did install our other plugin called 'Related Posts by Zemanta' on your Dashboard, just to see if the same thing happens — and it doesn't! :)
These two plugins are basically identical, so I would suggest you to use this new one I installed. But if you decide to have your blog related-posts-free, then you should be able to modify/delete that plugin without any problems.
But do let me know if this isn't the case or if you have any other questions what-so-ever — I'll gladly help!
Take care & have a nice day!