I am trying to use Daniel Berthereau’s Custom Ontology module (https://gitlab.com/Daniel-KM/Omeka-S-module-CustomOntology) and see that you cannot alter the ontology via its GUI form once initially generated. But it sounds like you can delete it somewhere on the file system and start over. This is what I want to do: Delete it, then recreate it with my edits intact. But where is it?
Any new Custom Ontology can be deleted from the Resources --> Vocabularies menu. Once deleted, you are then free to recreate it via the Custom Ontology module.