You don't normally need to uninstall Resolve from a Windows system to install a NEWER Resolve version.
Is installing 17.3.1 not working? Is that message screen shot you posted coming from a 17.3.1 install attempt? Or a 16 uninstall attempt?
If you have any current Resolve projects you care about backed up, you could use this Microsoft utility to uninstall 16. And see if that allows 17.3.1 to install:
https://support.microsoft.com/en-us/hel ... or-removedRun the app and it will automatically look for issues. If it doesn't find anything, it will present options for Uninstall and Install issues. Select Uninstall, and it will present a list of apps. Select DaVinci Resolve, and it should remove the current version, which should allow for the 17.3.1 installer to work.