Yes the Database design report will generate an HTML file that you can open in a browser and perform finds for the fields in question to see where they show up.
Thanks Mark, I just found this (wasn't quite to that chapter in my "Missing Manual."
Ouch, I was wrong, there are 600 fields. Looks like I have some work to do.
What I've done is rename a field if it's really generic such as renaming "Date" to be XXXXDate in Manage | Database | Fields, then run the database design report that comes with FileMaker Advanced. (If you don't have Advanced, get it, you'll need it.)
Then I can do a text search for XXXXDate and jump from reference to reference in the report. If the only places it is used are in areas that will be discontinued, it's safe to remove.
There are also third party tools available that you can web search for and investigate that may help you with this process.
And make lots and lots of back ups so you can revert back if you delete something and then change your mind...
Excellent tip, thanks Phil. And luckily I do have Advanced - whew!