My PC bricked that I used for ST the other day so I had to build a new one. With a fresh copy of Win10 Pro (1809) I installed a recent x64 standalone Beta but then decided to remove it to install my ASIO and VAC first. I uninstalled it but it did not remove the ST listing in Apps. I went into the regedit and got rid of it. Then I decided to try the x32 standalone, installing it and uninstalling it, it did remove the ST listing correctly.
I installed the x64 standalone again and uninstalled it, it left the ST listing there in Apps as before... then I installed the x32 standalone again and then uninstalled it, and it removed the listing in the Apps so there is no listing of ST in Apps.
I also tried this on my Win10 Home (1809) Laptop with same results.
I also tried this with Release v9.11 which also does the same.
So I'm guessing this has been there awhile unnoticed.
So to recap, if the ST standalone x64 leaves a listing in Apps, just install the x32 version and uninstall it and it will clean it up