MacOS – uninstalling adware bundled with adobe reader etc

My wife recently needed to install Adobe Reader for some of her work (apparently there is some kind of interactive functionality that Preview doesn't support) and in the process managed to install some adware as well.

I am trying to uninstall it, but cannot figure out how. All the guides I have found talk about how to uninstall it from various PC OS versions, but don't mention Mac.

At the moment there is one extension which shows up under Firefox on her account only: "Shopping Helper Pro 0.95.29", as well as a plug-in "Coupons Inc., Coupon Printing Plugin 1.1.0" which (for some reason) shows up both on her account and mine as well.

The problem is, I have disabled both of them in Firefox, but I cannot figure out how to actually install them. Supposedly an extension should have a "Remove" button" to uninstall it, but no such button appears. Plug-ins are said to have their own uninstallers, but I can't find one anywhere.

I am also concerned about whether these unwanted programs have confined themselves to just Firefox, or could be lurking in other places.

How can I completely remove all traces of both of these, or in general any kind of mistakenly installed (b)adware? It doesn't seem to be as simple as uninstalling an application where I can just drag a folder to the trash. Is there somewhere I can look (under System Preferences maybe, or another system application) to find and remark this junk?

Update: I discovered that the firefox config entry "plugin.expose_full_path=true" will let me see the full path to add-ons in about:plugins. In my case I found the offending plug-in in /Library/Internet Plug-ins and trashed it. However, I have not yet located the extension. It was not found in ~/Library/Application Support/Firefox/Profiles/[profile name]/extensions.