June 05, 2019, 12:19:26 am
The install of Lumion 9.3.1 will install Lumion to a separate folder and leave Lumion 8 there.
So you have both versions currently installed and working. That's so that if needed you can use Lumion 8, but that is almost always not required.
You can uninstall Lumion 8 by using Windows Apps & Features
and uninstalling it from the application list. Uninstalling only removes the software files, and leaves all your data in the Documents\Lumion 8.0
To transfer your user data for Lumion 9 please see step 1.4
in our Knowledge Base
article: Lumion 9.0: Everything you need to know
Uninstalling will free up about 20GB of file space on C: drive. For a good operation, you need to have at least 30GB at all times. So if you still only have about 20GB or so, then I recommend you free some more space by archiving some old files and projects and following the steps in Microsoft Help: Free up drive space in Windows 10
Let us know how it goes and if you have any more questions on freeing up file space etc.