You should be able to find it in the root\EditorNode
The types are EditorPlugins. If you don't know which it is, then it may be worth doing print statements in the plugin's ready code, or assigning it a name, and finding it by name.
Another alternative is inside the plugin code, you can assign a reference to it using
self on any property of an object it deals with, or if there are globals that you are using.