Follow the directions below to delete save games files from Disney Infinity games for Steam:
- Log out of your Disney account. Go to the Main Menu, then "Options", "Online Options", and "Log out".
- Close the game.
- Right-click the game in the Steam Library.
- Select "Delete Local Content", then "Delete" to confirm.
- Exit Steam: go to "Steam" then "Quit Steam".
- Delete the "Disney Interactive" folder in the App Data file.
- Log back into Steam.
- Reinstall and launch the game.
This will wipe everything except your DLC and Steam Achievements; they are linked to your Steam account.