[VOL-2748] Delete Device keyword support

Change-Id: I0600f455348bda0975eef43414fb0f23c9584b34
diff --git a/tests/functional/Voltha_PODTests.robot b/tests/functional/Voltha_PODTests.robot
index bcf59bf..cca0757 100644
--- a/tests/functional/Voltha_PODTests.robot
+++ b/tests/functional/Voltha_PODTests.robot
@@ -356,14 +356,12 @@
         Run Keyword And Continue On Failure    Wait Until Keyword Succeeds    ${timeout}    5s
         ...    Validate Device    DISABLED    DISCOVERED
         ...    UNREACHABLE    ${src['onu']}    onu=false
-        ${rc}    ${output}=    Run and Return Rc and Output    ${VOLTCTL_CONFIG}; voltctl device delete ${onu_device_id}
-        Should Be Equal As Integers    ${rc}    0
+        Delete Device    ${onu_device_id}
         Run Keyword And Continue On Failure    Wait Until Keyword Succeeds    ${timeout}    5s
         ...    Validate OLT Device    DISABLED    UNKNOWN
         ...    REACHABLE    ${olt_serial_number}
     END
-    ${rc}    ${output}=    Run and Return Rc and Output    ${VOLTCTL_CONFIG}; voltctl device delete ${olt_device_id}
-    Should Be Equal As Integers    ${rc}    0
+    Delete Device    ${olt_device_id}
     Run Keyword And Continue On Failure    Wait Until Keyword Succeeds    ${timeout}    5s    Test Empty Device List
 
 Validate authentication on a disabled ONU
diff --git a/tests/functional/Voltha_ScaleFunctionalTests.robot b/tests/functional/Voltha_ScaleFunctionalTests.robot
index 4c79738..44ae691 100644
--- a/tests/functional/Voltha_ScaleFunctionalTests.robot
+++ b/tests/functional/Voltha_ScaleFunctionalTests.robot
@@ -197,6 +197,5 @@
     Should Be Equal As Integers    ${rc}    0
     Wait Until Keyword Succeeds    ${timeout}    5s    Validate OLT Device    DISABLED    UNKNOWN    REACHABLE
     ...    ${olt_serial_number}
-    ${rc}    ${output}=    Run and Return Rc and Output    ${VOLTCTL_CONFIG}; voltctl device delete ${olt_device_id}
-    Should Be Equal As Integers    ${rc}    0
+    Delete Device    ${olt_device_id}
     Wait Until Keyword Succeeds    ${timeout}    5s    Validate Device Removed    ${olt_device_id}