Same as any other analysts really, find the SA analyst right hand click and change their password. You ask about LDMS, but the SA account isn't used in LDMS. For the version of LDSD you are using there is no need to use the SA account for very much else. The ConfigurationCenter has it's own, separate SA account, so you might want to change the password there too.
The tool that used to be used for updating the SA password in other spots is called TouchpaperPasswordTool.xe and lives in the AppServices folder of the ServiceDesk install area. I'd hop onto a test system and make the changes there before pressing the button in PROD