We are running KC2016 SP1. This help topic states: 

• To deactivate a user, uncheck the Active box. This allows the user value to be maintained in the repository but eliminates the name from user lists. For instance, when a user leaves the company but is associated with metadata for an object, such as Last modified by, the username (data) in the field is maintained and valid however, the user no longer appears in any lists.
• Check the Disabled box to prevent the user from logging into Content Manager. For instance, if the user leaves the company.

However, after deactivating users, they are still appearing in dropdowns in selection dialogs. Based on my reading of the help topic, I thought they would be removed. Am I doing something wrong or did I just misunderstand what 'deactivating' a user actually did? And if so, is there some way to reduce the selection lists for users to just be 'active' users?

Thanks!