Reset RimWorld's configuration data by deleting all the RimWorld configuration files. You'll find them in one of the following folders (depending on your operating system):
Windows C:/Users/[username]/AppData/LocalLow/Ludeon Studios/RimWorld/Config
C:/Users/[username]/AppData/LocalLow/Ludeon Studios/RimWorld by Ludeon Studios/Config
Note 1: the AppData folder may be hidden.
Note 2: the RimWorld folder within LocalLow may differ for various users, see this thread
• Paste this into a Run Window on Windows 10: %userprofile%/appdata/LocalLow/Ludeon Studios/RimWorld by Ludeon Studios/Config
Mac Users/[username]/library/Application Support/Ludeon Studios/RimWorld/Config
Users/[username]/library/Caches/RimWorld/Config
Linux /home/[username]/.config/unity3d/Ludeon Studios/RimWorld/Config