Funny, I recently wanted to uninstall a bunch of fonts I tested for programming. Turns out, in the new font settings widget you cannot uninstall all fonts or even all styles of a font at once. I would have needed to select a font, then click "Uninstall" for the bold style, the semibold style, the medium style, the italic bold style etc.

Opening \Windows\Fonts instead gives you a nice view of all fonts, you Ctrl-select all you want, right click, uninstall, done.