Gideon, you may know all the answers and not be confused at all about those answers. But until you know which answer to give, you will remain confused. The fact that you didn't interpret the word "no" proves it. I didn't come in to start an argument. I mentioned what I did to bring it to your attention, plain and simple.
Back to the topic:
Single tab closure is simple. Click the X in the tab, not the browser X or group X. I've yet to see a browser (or any other application for that matter) that didn't work that way, if there was no option to also close from a right click context menu. And if for some reason that fails to work, there is definitely something wrong with said application.