First of all, you might want to use paragraphs in your posts. I don't know if that makes a difference to someone using a screen reader but it surely makes a big difference for sighted people -- your post as-is is extremely hard to read and follow since it's a single big "blob".
In trying to uninstall the bootloader, I first click enter on utilities, then rockbox utility V1.2.6, then RockboxUtility.exe.
Rockbox Utility 1.2.6 is totally outdated and you won't get any support for that here. Blind people keep claiming that you need to use that version, this is nonsense. There is an issue with voice file creation with later versions but that has been fixed. Furthermore, it only appears when you try to create a voice file and only if you are using a SAPI voice on Windows. If you install the prebuilt voice file there won't be any problem at all.
There are also recent development binaries available that don't have problems with voice file generation. See the link in my signature.
At this time I get a message "update available with an OK button". What does this mean. What is the update. Is it an update fore the fuze firmware?
It means that an update is available. Rockbox Utility 1.2.6 is totally outdated -- it's been released almost 2 years ago. Of course it does NOT refer to the Sansa firmware, because when starting Rockbox Utility it doesn't know about your player -- you haven't configured it yet.
If so, I don't want to update the sansa firmware as I heard it lowers the volume of the player and causes some other changes that aren't as good as the origional firmware.
We don't care about the original firmware.
At this point I hit the enter key on OK and go to the menues right arrowing to actions and then to uninstalation. Clicking on that, it says "remove bootloader." When I click on that, and click yes to confirm, it says "no uninstall method known". Can anyone tell me why this is happening and how to uninstall and then install bootloader and rockbox again with all my voice files.
Yes, Rockbox Utility can. When using a recent version.
Can I do this without updating the sansa firmware? Am I correct in understanding the original firmware is better than the updated firmware fore the V1?
You're mixing up things. The original firmware is necessary to install the bootloader, since the bootloader is added to it. However, when starting Rockbox the original firmware is not used, it's only purpose is to start Rockbox (via the Rockbox bootloader that has been added to it). So this original firmware vs. updated firmware doesn't make any sense.
Also, if I save the good rockbox with its config files on my computer, could I get everything back by just copying it back in to the player if something goes wrong?
Yes, with the exception of the bootloader.
However, I'd strongly advice not to mess with the bootloader. If you have a working bootloader just leave that in place. There's no harm about it. However, if something goes wrong when fiddling with the bootloader you might need sighted help or even might brick the player. What you want to (un)install is Rockbox, not its bootloader.