The Symantec Workflow Server service is running on the Notification Server. You question if you actually need this service since you do not use ServiceDesk or the separate WorkFlow Solution.
ITMS 8.x
This is by design.
The installation of the Symantec Management Platform includes the installation of Workflow Solution and portions of the Symantec Management Platform use functionality provided by Workflow Solution.
The removal of either the Symantec Workflow Solution or the Workflow Solution service will cause issues with the Symantec Management Platform so these should never be removed.