As answered in another thread, this is the solution to make this plugin work:
First you need to check that the user you are using is a super admin. It doesn't show up with other inferior user roles.
Second: The plugin only works if WP Super Cache is active. Please check that it's active.
If both plugins are active, you will find an additional menu entry in the header of the WordPress administration.
Here you can see a screenshot of the spanish version in english it will be at the same place and read: "Clear all cached files".
Nevertheless, if you only need to empty cache of one page, when viewing this page while logged in, you will see a menu entry that reads: "Clear cache". This clears the cache of the page being displayed.
The advantage of our plugin is that you can clear all cache from the menu, not only the page you are viewing. So probably you don't need our plugin.
Hope this has helped.