Just do what the message says:
Uninstall it first, then run this installer again which will install the current version. SODE its listed in the Windows Control Panel as SimObjects Display Engine...
I'm not sure what else the message should say. It says:
- What you should do first: which is uninstalling SODE
- What you should do next: running the GSX installer again
- What SODE is "Simobjects Display Engine"
- Where it can be found to uninstall it: in the Windows Control Panel.
Really, the message already included all the information you needed to proceed. Like any other Windows program out there (this is no different), it can be uninstalled in the Windows Control Panel, in the "Program and Features" section.