Newbie question re editing context list
 

I've been using OF sporadically since it was in beta, but have fallen off the wagon a couple of times. During those false-starts, my context list has become cluttered with contexts that I no longer use, as well as "Welcome Contexts" that I loaded, but can't seem to get rid of. Since my Projects and Actions aren't that up to date anymore, I decided to uninstall OF and reinstall, re-building my Projects and Contexts from scratch. No problems there, following information that I found on these forums.

I just bought a license and am setting OmniFocus up again, but can't for the life of me figure out how to delete some of the contexts that come pre-loaded. For example, I don't want Mac, Mac: Email, and Mac: Online, I just want Computer. Also, I have no use for People, People: Spouse or People: Boss.
I thought that I could simply delete all the items that have been marked with those contexts, but I don't see any items with them to delete. Have searched the forums but didn't come up with anything that addressed this issue. I'm sure there is an ultra-obvious way to do this, but I'm stumped. Can anyone shed some light? Thanks--

Below the context list in Context mode (the left-hand pane or sidebar) there is a series of icons: plus, minus, and gear. You should be able to delete a context by selecting it and pressing the minus icon.

Thanks--I didn't have the view set to "All Contexts".