Hi Jim,
I am a "novice" but I am wondering since you want to do basic file renaming, the best would be use a script shell (.bat on Windows) or server script (ASP/PHP/Python, etc.) depending where the files are located.
For Visual Basic, please have a look at the Split() function.
Split function (Visual Basic for Applications) | Microsoft Docs
You can just split the string at the "-" delimiter and retrieve the last value of the array (you will have to remove the empty space of that last value)