As Phaze said, the "Info" button is your friend. It will tell you which tournaments were loaded, which passed the filter, etc. So use it to identify the tournament that doesn't belong. To get it out of the mix, delete the tournament. Tournaments are saved as files, so use the Info button to get the tournament filename, then use Windows Explorer to find and delete the file.
But be sure of what you are deleting. You might want to load the tournament first and check it out before you do anything drastic.