It is not possible to delete an User (Local Account) in Symantec EDR.
Symantec EDR 4.x
This is by design.
Currently, the operations available for managing local accounts are Creating, Enabling and Disabling. An user can not be deleted. Deleting an user would have implications on tracking the operations initiated by this user.
Instead of deleting it, a Local User can be disabled.
Symantec EDR - Managing users