A while back, I created a website shortcut using the now discontinued Prism extension for Firefox. This worked fine at the time. However, now that Prism has been discontinued, whenever I open Firefox, when the shortcut for FF shows up my Windows taskbar, it does so with the website favico for the old Prism shortcut site that I created. If I right-click on the taskbar shortcut, it shows the old shortcut to the Prism app (even though I deleted its entry manually from C:\Users\USERNAME\AppData\Roaming\WebApps). If I then click on [Pin to Taskbar] and then right click and [Unpin from Taskbar], the icon will switch back to the FF icon. If I righ-click on it a third time, it will switch back to the Prism site favico.

I assume that if I were able to install Prism, then it would give me some way to remove the site. However, since Prism is discontinued and incompatible with the current version of FF, that is not an option.

What I would like to do: completely remove references to the Prism app from my computer:

1. Disassociate the prism website Favico from Firefox, so that it never replaces the FF icon in the Windows taskbar
2. Shortcut to the Prism site will never shot up in the right-click menu for FF