I succeeded by deleting the C:\Users\Stéphane\AppData\Local\Sector3_Studios_AB ,and uninstall the RaceRoom Dedicated Server program and delete its directory. Be careful not to get the word "ask" wrong on the web page when restarting.
Okay that helped, but I only did "deleting the C:\Users\...\AppData\Local\Sector3_Studios_AB" Of course in this case you had to completely configure the server(s) from zero.