RED IM will always maintain record keeping for any systems it comes in contact with for licensing and auditing purposes.
This could be system information or password information. Over time if a managed system becomes decommissioned then there are ways to automatically or manually remove the system from the RED IM managed structure.
For example when you open the Orphaned Systems dialog, it will display only systems that are not in any management sets and not included in any jobs. To show systems still in jobs, clear the check box to Hide systems that are found in password change jobs.
To fully remove the system (not including passwords) from the database, highlight the system(s) and click Delete System from Database. To re-add the system to a management set, highlight the system(s) and click Move System to Management Set.
If you only delete the system, then RED IM will retain the password information for the managed system. System information and Password information are separate structures in RED IM. You can delete the password information in the View Stored Passwords dialog or from the RED IM web application as an all access user or user with Add/Edit/Delete permissions.