You may have to nuke the entire installation and reinstall,

There are two directories, the "Game Reference Directory" and the "Game Data Directory".  The function of each is:

Game Reference Directory - are the game executable files are stored

Game Data Directory - where your personal game saves and such are stored

The directory locations can be found in the Administration section, click the directories button.

Then find both directories, be aware some file managers hide some directories by default - google how to display those.

Your problem sounds like it is coming from the Data directory. So you can try to delete that first.   But removal of both and then a reinstall will completely clear the game off your box.