Anyone know if Win10 System Restore will successfully roll back a Cubase 9.0.20 to 9.0.10?
Just uninstall the update.
How do you suggest to do that?
There is no entry in the list of programs in the control panel to uninstall the update, only to uninstall the entire Cubase.
I did my own test on this, and although it appeared to work and said it had completed successfully, in actual fact it broke Cubase, leaving my with a Cubase which would launch, but with no Project Window. Nada. Gone. And I could not resurrect it after some time of trying.
So System Restore is not the answer.
Yes there is, you may have to enable it to show updates in the control panel.
https://www.steinberg.net/forums/viewtopic.php?f=250&t=116775&sid=6c52da6f1b835e730fef9bb35e5f2f35
last time answered only two days ago, and several times before… 
Well its obviously quite important then…
Thank for that. Don’t think you can do that in the new style Win10 app manager. At least I can’t see it.
In Win 10…
Start>Settings>Apps>Programs and Features>View installed updates.
Scroll down until you see “Steinberg Cubase 9.0.20 Update”
“Programs and Features” is on the upper right side.
“View installed updates” is on the upper left side.
Regards. 
Cannot see those controls in the new style Win10 interface on my machines. I have to open the old control panel to get at the “View Installed Updates” feature.
I wish MS would commit to this new interface and complete the set of tool available in it.
I wonder why your Win 10 looks different than mine? This procedure has been the same for every update of Win 10 that I have updated to. Weird stuff for sure.
Good luck.
Regards
Quick way to get to the old interface:
Open the Windows Run dialog (Windows-R) and paste:
Control Panel\Programs\Programs and Features
Another way an imo easier way is to start the 9.0.20 installer again. After scanning It will find and display the currently installed items and here you can choose which ones to remove.