What version of Windows is this on? Although I’d concur with @Stanley_4 ‘s solution. There should be no danger in deleting any controller, since it is only a window through which you can see what is happening on your Sonos devices. Just ensure you use ‘Connect to existing system’ when you reinstall.
It might also be interesting to confirm what system devices are running with S1. I’m wondering if some of them can be upgraded to S2.