Updated: December 22, 2018
If you're using the Gnome desktop, due to its minimalistic nature, you must have been exposed to the concept of extensions, and probably used some. The workflow is as follows: you install a browser extension and the shell package, you install extensions through the official website, and then you tweak the extensions on/off through the Gnome Tweak Tool. But what if you want to remove an extension? Permanently?
It is quite easy to add extensions, and also very easy to toggle their state, from enabled to disabled, and vice versa. However, turning an extension off does not actually remove it. So how does one go about uninstalling Gnome extensions? Let's see.
Easier and more complicated than you think
On one hand, you probably expect a tool like Gnome Tweak Tool to offer an uninstall facility, but it's not there. Then, as a Linux person, you're now thinking, which directory holds the extensions. You might want to use the command line, navigate there, and then just delete this or that entry. Doable but unnecessary.
What you want is the aforementioned web interface. You install - and uninstall extensions through the Gnome website. The browser extension allows you to manipulate the filesystem, and that means both adding and removing content. On the Gnome extensions page, click Installed extensions. Or you can just navigate to:
This will display all your installed extensions. Click on any X button to remove the particular entry. Extensions that are in use may not show the uninstall button. I don't know what the rule is for when the red X is displayed, though. You won't get a second prompt. Don't worry if you do remove one or two unintentionally, you can easily reinstall them, and your settings will be preserved.
In my case, it was the simple matter of having two Show Desktop buttons. This bothered me, so I had one removed. The facility works fine, and you do not need to do anything special. There's no need to reload the desktop or log out. The changes are immediate.
There you go. As a typical desktop user, you will probably not think about going to the Gnome extensions page to manage your uninstalls, especially if you've installed some a long time ago and not really thought much about this unusual way of how Gnome managed third-party content. In this regard, I like the Plasma integrated addons manager better, as it also extends to themes, icons, wallpapers, and other desktop elements.
Like I said, it's dead simple - but you do need to remember the unconventional way of how it's done. Anyway, I hope this little tutorial gave you some peace and clarity. If you have any other requests regarding how things are done in Gnome, or any other desktop environment, now is a good time to exercise your email skills.