You uninstall SEP through Programs & Features with the intention of removing all SEP-related entries from the machine.
However in Task Scheduler, three tasks still remain:
SEP 14.3.*
This issue is fixed in Symantec Endpoint Protection 14.4. For information on how to obtain the latest build of Symantec Endpoint Protection, see Download the latest version of Symantec Endpoint Protection.
Workaround: