How to uninstall a text format created by a D8 module? My module creates its own text format upon installation by having a file named config/install/filter.format.{format}.yml.

However, I can't uninstall and reinstall the module, because the format persists and will then cause a conflict. ("... already exists in active configuration.")

This looks like a bug in the filter API, but maybe there is some explicit way to delete the format when the module is removed? It's really annoying to have to manually delete the config key every time.
You need to add a dependency in your filter format to the module. Then when the module is uninstalled, the format should get deleted