If I understand correctly, you installed WordPress 4.1 with its default theme and then installed the Force Login plugin; then tested and confirmed it works.
You said you only installed/activated one other plugin, the “AD Integration” plugin:
https://ww.wp.xz.cn/plugins/active-directory-integration/
I assume your issue(s) started after you installed and activated that other plugin? If you deactivate and/or uninstall the other plugin, does the Force Login plugin work correctly again?
I don’t know what you’re referring to when you say “back to wiki,” I assume that is something that gets added to the login screen by the other plugin?
I can click on “back to wiki” at the bottom of the login page, choose log out and then I can get in.
And, you’re having trouble with what exactly?
You started to say it “loops [you] to the login screen only,” which I would assume means the site is not recognizing you as being logged-in and thus continues to redirect you to the login screen until that condition is met.
However, you also asked, “Is there a way for the plugin to kill a logon session … ?,” which I would assume means you are able to login–but can’t logout?
Force Login only checks for logged-in WordPress users and considering you’re using another plugin to authenticate a logged-in user with a third-party service instead, likely this plugin can’t determine if you’re logged-in or not as a WordPress user.
TL;DR
I suspect your issue is not with this plugin alone, but instead with the combination of this plugin and the other authentication plugin you’re using.