How can we clear the 'recently viewed managers' list under Act as Proxy Manager?

Summary:

Our security is working properly to restrict the managers that an admin is able to search for under Act as Proxy Manager. However, the list of recently viewed managers is not clearing and allows access to a manager who used to be appropriate for a given admin to view, but they no longer are appropriate due to transfer or promotion. When these movements happen, the manager is no longer accessible under Search, but is still in the recently viewed list and if selected then their plans are viewable by the admin who should not be able to view