[GNC] how to remove both GNC 4.2 and Flathub version 4.8 so can upgrade to 4.9 on Ubuntu 20.04lts

[Jeff]

I currently have GNC Version 4.2 installed on Ubuntu 20.04 LTS. At the 
recommendation of a former post for info I also have 4.8 from flat-hub 
somewhere on my system (have yet to find out where or how to remove it).

4.2 is is in the launch bar and has desktop icons to multiple sets of 
books.  The only way I have found to run 4.8 is in software manager and 
have to change books manually (which 4.8 also had the nasty habit of 
creating backup files on the desktop for some reason).

1) How do I uninstall both versions?

2) how do I install 4.9 (preferably without Flathub)?  I also need 
desktop icons to launch GNC from the desktop for multiple sets of books 
(lucky me, I am the accountant/tax man for the entire family!  I won't 
even go into what condition I receive financial records in).

I am not opposed to building from source code but; all of my tries have 
so far failed miserably on GNC.

It's a simple mater under Windoze but so far nothing I have tried works 
on Ubuntu.  And yes, I need the desktop icons for each set of books as 
the icons are linked to each individuals books across multiple drives on 
remote servers not just mine. My memory has had to many read/write 
cycles to keep track of who is on which server drive and file name.

-- 
--JEffrey Black M.B.A.