I have tried everything to delete Calendar and To Do Categories.  I have deleted all things that have to do with these categories yet they still show up in the list to select when creating a new entry.

I have went to Preferences > Calendar & To Do > Display > Entries and deleted everything there.

I have deleted ALL of my To Do entries and ALL of my calendar entries ... yet when I go to create a new calendar meeting, and select Category, I have "Holiday, Vacation, Projects, Clients, Phone Calls, Travel, Admin, Training, Vacation / Holiday, Personal" in the list to select. 

Please, I only want 4 things there so I don't have to scroll looking for what I want to select each time.  How, do I delete them?