Thank you for this suggestion! Sadly, Categories IS installed... Maybe reinstalling is an option? It says - when I want to delete it -
WARNING
The following packages depend on package categories that you are about to delete:
project-manager
lars-blogger
Proceeding with the deletion of the package may render the system in a broken state.
Deleting a package removes all record of it from the APM's database.
We recommend sourcing all of the drop scripts for the package. Be aware that this will erase all data associated with this package from the database. sql/postgresql/categories-drop.sql