How do you delete feat/spell/special ability filters that are no longer applicable?

[Faolan the Azure Abjurer]

One issue that I and a few other fellow GMs have been experiencing and have found no answer to is this:

Say we manually key in a spell from a physical book we have on hand (the game in question is Pathfinder 1e) and we make a mistake in entering the spell's class and level in the description or decide to change how it's formatted, how do we then delete the Source or Type filter that now has 0 entries associated with it? We have all these useless filters now and can't figure out how to get rid of them.

For instance, when making a Witch character, there ended up being two different abbreviations used to help filter spells for Witches. Wtc and Wth. We changed the spells so they all have the same abbreviation, but then the other abbreviation still showed up as a filtering option, despite there being no spells in that category.

[Trenloe]

The filters are updated, and held in memory, once a new value is made. As you found, they are not removed when the final record related to a specific filter value is deleted. However, when you next load the campaign and open the campaign data list, the filters should be populated with current values only.