Try: Substitute ( Upper ( text ) ; "C" ; "" )
And that substitute function can be used with Replace field contents if you want to make a "batch" modification of this text field. (Save a copy of your file first, just in case you make mistake doing that.)
Also keep in mind that Replace Field Contents or even looping script will not protect from failure if a record is locked so run this when no Users are in the system or, what I've done on occasion, simply perform a find for 'C' in that field afterwards to verify they all were stripped and if not, run it again. :-)
That worked perfectly! Thanks very much for your assistance.