Hiding Obsolete Items from the Basic Search
you need to check and review configurations associated with objects.
Please check thoroughly the Criteria of non routable objects like parts and documents and its associated, privilege masks that are mapped with roles.
Basically, all the roles impact will give insight of impact user having those roles
or role mapped to usergroups associated with the impacted users
Also, review for other users who are not restricted.
This will give impact of change to meet you objective.
Change that need to make in configuration are by adding additional conditions by specifying needed life cycle phases other than obsolete in the criteria associated with privilege mask of read and discover privileges in existing roles for the users who do not need access
For those users who need access create separate criteria and map privilege and roles with separate user groups..
This will ensure, your access control of data is in place for all users.