When you uninstall GIMP and remove GIMP 2 in the Program Files, GIMP have a User folder that you have to remove manually. This folder is in your user profile:
C:\Users\YourName\AppData\Roaming\GIMP\2.10
RC file store your setting and when you open GIMP you have your setting back
Go to the directory mention above and delete all your rc files. Don't worry, GIMP will generate these files again with a fresh start.