NTP server cleanup

resolves openbmc/openbmc-test-automation#1875

Change-Id: If00814efb907495acb0b4077357116a5bac529fd
Signed-off-by: Sivas SRR <sivas.srr@in.ibm.com>
diff --git a/redfish/managers/test_managers_bmc_time.robot b/redfish/managers/test_managers_bmc_time.robot
index cf75895..bab3ec3 100644
--- a/redfish/managers/test_managers_bmc_time.robot
+++ b/redfish/managers/test_managers_bmc_time.robot
@@ -193,4 +193,6 @@
 Suite Teardown Execution
     [Documentation]  Do the suite level teardown.
     Rest Set Time Owner
+    Redfish.Patch  ${REDFISH_NW_PROTOCOL_URI}
+    ...  body={'NTPServers': ['${EMPTY}', '${EMPTY}']}
     Redfish.Logout