Hi Tim, sounds like some kind of problem is afoot. Just to clarify, if you click the Remove link does absolutely nothing happen or do you get the alert window displaying the following text:
Are you sure you wish to remove this field and its data from all events? Once you click OK this cannot be undone.
Can you also confirm which version of The Events Calendar and Events Calendar PRO you are using? Something you could try is following our standard troubleshooting steps:
- Deactivate all other plugins except for The Events Calendar and Events Calendar PRO
- Change your theme to a default, unmodified theme such as Twenty Eleven or Twenty Ten
- See if you can now remove additional fields
- If you can, reactivate everything one-by-one, testing at each stage, until you (hopefully!) uncover the conflict
It certainly is something that should work, there ought to be no need to edit the database directly.