Hello,
You can Either Run the CleanWipe Utility for 12.1, which you can get from the Symantec Technical Support.
NOTE: It is not Recommended for you to use CleanWipe Utility on Server Operating Systems.
I would suggest you to Go through the Manual Uninstallation Steps.
Here are the Articles on Manual Uninstallation of Symantec Endpoint Protection 12.1
How to manually uninstall Symantec Endpoint Protection Manager 12.1 on all Windows operating systems
How to uninstall Symantec Endpoint Protection 12.1 client from Windows Vista, Windows 7, and Windows 2008 32 and 64-bit operating systems manually
Hope that helps!!