Okay I found a very old post that ted replied to.
In your UBB.classic control panel, click on General Display Settings. On that page, look for a setting called "Last Post Column Options:" under the "Forum Display Options" section of that page and you'll see 4 options:
Disable Last Post column
Enable Last Post column - time only
Enable Last Post column - time & name link
Enable Last Post column - name link only
I also see in the manual there is a "Last Post Column Options" under Forum Summary settings also.
I don't know if this will do what you want but give it a try.