Access is denied.
By default, it is not possible to kill a process that is running under a security context different than the one of the process who issued the call to TerminateProcess. It is possible to end any process even though it is a service or a system process by previously enabling the debug privilege. This privilege is assigned to Administrators and is disabled in the access token. While Task Manager does not make use of the debug privilege, the KILL utility does. You may assign this privilege to users other than Administrators with User Manager.