The columns will be coming from one of the formats you haven't looked at. Either a Content Type format or one of the lower-down formats that a higher format is inheriting columns from.
Have a read of the FAQ, or just edit all of your formats to be sure the columns are gone.
Also, close any existing listers in case they're remembering previous formats. (It's useful sometimes but can be confusing when you're trying to verify the results of editing your formats.)