I hope it works for you. I have never uninstalled a driver instead opting to disable it. Uninstalling a driver may cause Windows to re-enable it should it decide to update the missing driver.

GjB
(Windows 10) Control Panel - System - Advanced System Settings - Hardware (tab) - Device Installation Settings -  Do you want to automatically download manufacturers' apps and custom icons available for your devices? - Check No.
 
This will stop Windows 10 from installing drivers over the top of the ones you are manually installing and trying to use.
So, if Windows has reinstalled drivers which you don't want, do the above and then manually reinstall your preferred driver (and reboot). (Also, if you don't use some devices, then you can safely disable them to limit potential compatibility issues.)

Well I followed your directions to the letter.  I checked the audio playback and recording tabs, and the only device showing now is the Saffire driver.   I turned off option you mentioned in the Advanced system settings.
All seemed okay, until....
I rebooted my PC, and *crap* ALL of the computer manufacturer's HD audio devices and drivers reappeared, and the one that was enabled before, is now enabled AGAIN!

I checked out the other thread, and read all the posts.   I think I might have to go into the registry to permanently get rid of these drivers and to stop them from coming back every time I reboot or restart the computer.

The unwanted drivers return, and one is enabled:

I wouldn't do anything in the registry.
I also wouldn't worry about things appearing in the list. Just make sure that the one you want is the default and it should be OK. My above instructions are just to stop Windows reinstalling manufacturers' drivers over the ones you choose to manually install.
 
So for example if Focusrite or someone gave you a driver, or you use an older driver which works perfectly, then Windows won't try to replace it with something else.
 
Edit: Do what Scook says below, too.

I used Windows Control Panel > System > Device Manager > Sound, video and game Controllers  and disabled everything I do not use.

Okay thanks again for all the advice, I really do appreciate it.

  But I'm sort of back where I started from.  After disabling everything I don't use, after rebooting my PC, I'm still getting one of the HD Audio drivers from the computer enabling itself again.
And the Saffire MixControl software is still changing ASIO buffer size on it's own. 
I've also noticed that Sonar takes a very long time to load a project, even a small one. Sometimes taking up to a minute or two to open. (when normally it would only take a few seconds)

And reading through many forum posts here, as well as Googling trying to find some answers, I'm finding an endless amount of information that often contradicts each other.  So I'm just a bit frustrated.
Especially after Sonar has been virtually rock solid for me, for so many years.  And now when I want to start working professionally with it, it's become unreliable.  I was nervous enough worrying about how well I can work with paying clients (based on just my own skills and talent), now I've got this whole new level of uncertainty which seems like it's totally out of my control.  *sigh*

have you tried disabling the onboard audio ("high definition audio device" in your screenshot) in the BIOS? windows won't even know it's there then, and so won't load any drivers for it

The Windows 10 Fall Creators Update is going to start trickling out in 2 days' time on the 17th.
So when the ISO of that becomes available, if you want the latest version of Windows 10, then you can do a fresh Windows 10 install and start from scratch. That's what I plan to do, and millions of other people I expect.

pwalpwal
have you tried disabling the onboard audio ("high definition audio device" in your screenshot) in the BIOS? windows won't even know it's there then, and so won't load any drivers for it

Okay, I'll give that a try. I know my way around the BIOS settings much more than the registry.
Hopefully that'll work.  Thanks!

GjB
The Windows 10 Fall Creators Update is going to start trickling out in 2 days' time on the 17th.
So when the ISO of that becomes available, if you want the latest version of Windows 10, then you can do a fresh Windows 10 install and start from scratch. That's what I plan to do, and millions of other people I expect.

I've had to do fresh Windows installs in the past.  Even with all my DAW software backed up on an external hard drive, reinstalling all my programs is the biggest PITA I've ever had to deal with.  Doing a fresh Windows install, removes all your personal data and software, and even if I have everything else backed up, installing hundreds of programs, plugins, and efx software, INCLUDING having to get much of that software re-authorized, is a project that takes several days!  Often I can't just re-authorize software automatically.  I have to contact the software company, either by phone or email, and wait for them to help me reauthorize it.

It's by far, a very LAST RESORT.  Starting from scratch, after having to do that (about 6 or 7 times already) whenever I get a new computer, or if I have a major hardware failure, is definitely not something I would want to do again, except when there's no other alternatives.   Even when I mirror/ghost copied the complete hard drive, specifically meant for easy transfer from one drive to another.  I still ended up having to manually reinstall and reauthorize much of the software that I was transferring.

I understand exactly. But hopefully there can be bug fixes in these large Windows updates, especially like webcam issues after the Anniversary Update and audio issues after the Creators Update.
This is not my livelihood, so I'm happy to reinstall at a moment's notice.
More often than not for many people, a reinstall fixes their issues, but not always.