I realize this reply is late, but I just installed this Wp-Admin-block plugin and now I will delete it completely.
It works well to redirect me to my home page for the blog, but there is NO place to enter the keyword and the plugin does NOT offer any login box or page to enter the friggin security key. It just keep redirecting.
The way to deactivate this useless plugin is to first open a new tab in your browser. Go to your website host, login and go to the C-Panel of your website host company.
Most of them offer access to your site file structure (folders and files). Once there for your blog, do the following:
> click folder “wp-content”
> click folder “plugins”
> rename folder “wp-admin-block” to anything, I renamed it to: “wp-admin-block-OFF”.
Now it is deactivated, open the tab that has your blog, click the login link for your blog and login.
Once logged in, you have the WP dash board.
Go to your plugins inside yor WP Admin console and delete the friggin thing.
Do not return to your C-Panel to rename the wp-admin-block folder back to its original name, it will block your access to the plugins again. Just delete the plugin in WP admin plugins page and it will delete it from your WP files and folders.
I won’t bother hassling with defective plugins any more, I just delete them and find something that works.