How to delete hidden desktop widgets?

I added Web browser widget to the panel and when I tried to move it from the panel to the desktop, it disappeared. However, it still showed in the widgets menu, as a blue number next to the widget. So to try and figure it out, I did this a few more times with the same result and now I have a bunch of “invisible” widgets on the desktop, which I’m not sure how to actually remove.

Is there any other way I can find them?

It’s in ~/.config.