Delete Attribute from List

I've been using Mezzmo for a while, and the update to version 5 was a significant change to the program. I trying to figure out how to remove an attribute from a list. Example, in Genre, I have a entry for "Horror Western", but it should be "Horror" and "Western". In most programs, to delete an entry, you select it then Ctrl+Delete, but this doesn't work for Mezzmo's attribute lists. Suggestion/Solution?

Hi,
Mezzmo will clean up the list to remove this entry when no files contain the genre so you will need to edit the properties of files in this genre to change the genre then run Maintain Library and the genre should be removed.