I have been staying out of this thread because you indicated that you were waiting for Bizarrebob to reply.
I see he hasn't been online since Oct 2nd 4:42pm and probably would not know that you are waiting on him.
Since you are still having difficulty, I've decided to reply.
First a note: My own direct experience with FireFox, has been entirely favorable. I've even been able to use Add/Remove to uninstall older versions, prior to installing update versions. So I was initially dismayed to find that you were having problems with it. I, too, have been eagerly anticipating the response you were awaiting, in hopes of a "magic-bullet" type answer. When I realized that you might be having more difficulty uninstalling Mozilla/FireFox I set in motion a series of searches and inquiries at various online resources.
My search has found that many others have had difficulty, similar to your own. Further, I've found that there are few resources to turn to in this matter. Finally, I've found that the few resources, have ultimately lead to successful uninstall/reinstall.
As a first step in trying to assist you, I will post the URL's to the resources where successful assistance was obtained by others. Please read them thoroughly. We will then have a common basis to proceed, and I will make myself available to assist with any steps that may be challenging to you.
Here's the resources:
I am hopeful that this will give you a place to start, and look forward to any of your additional questions.