Tom, since we have an active CtagsInterface maintainer (good job), I'll step up with a feature request.
Most of my projects have a "Dialog" method. And many methods with repeating names. So I chose to always remove old tag sources (e.g. an old project) through CtagsInterface option pane. That's a bit inconvenient way to clean all the sources. Don't you think a command like "Remove all sources" would be handy?
Or maybe I need an advice on how to properly use the plugin. Note that I not only tag projects. Sometimes I tag directories.