Today was the first day I ever opened Adobe Audition (link). As with most Adobe software, I personally find it very un-intuitive, and almost impossible to figure it out just by hunting around. So I had to look up how to do something as simple as trimming an audio file.
This requires the ‘razor blade tool’ (screenshot). Note that it will be grayed out and unusable in the ‘wirefom’ mode; it only becomes visible and clickable in the ‘multitrack’ mode.
Once you click that, you can clip you audio track wherever you like, then simply delete the extra part. Pretty simple, but not easy to figure out without someone telling you.