Launch the Symantec.ServiceDesk.Setup.msi and use the uninstall option for ServiceDesk and Workflow. Verify both uninstalls complete successfully.
Right-click the Symantec.ServiceDesk.Setup.msi, and select Uninstall. This will uninstall the actual ServiceDesk setup files from the machine.
Navigate to C:\Program Files\Symantec\ServiceDesk Setup and verify that all files were deleted. If not, delete any remaining files from this folder.
Navigate to C:\ProgramData\Symantec\ServiceDesk, and delete the version of Symantec.Workflow.Setup that is there. This step is optional, because the ServiceDesk installer will ask you if you would like to download a new version of Workflow from your SMP when you run the Workflow Install portion of the installer.
Open IIS Manager
Click on Application Pools
Confirm ProcessManagerPool & ServiceDeskPool don't exist. If these two application pools exist delete them.