There are 2 family's of settings:
Per Library (like custom columns) that are part of the DB and what the prefs...Json file saves as a restore tool
And
Per User, (AKA the configuration folder). Thes stor you plugins, overall settings that are not Per Library
Un-installing removes none of these.
You would need to destroy Metadata.db (which is the Library brains), to destroy custom columns. Not a good plan
