Most of the components that ISVs can remove/delete from their managed packages still exist in customer orgs that have the package installed.
I want to provide my customers with a list (Visualforce page) of such elements so that they know what can be deleted.
I know that I can SOQL-query Objects, Fields,
ApexComponent, but how do I find which of the results are those deletable items. They still look the same and now have a Delete button enabled in the Setup.
NOTE: Still fully unsolved. None of the answers helped to solved this.