diff --git a/tempest/clients.py b/tempest/clients.py
index e3466e5..838f128 100644
--- a/tempest/clients.py
+++ b/tempest/clients.py
@@ -40,12 +40,11 @@
     }
     default_params_with_timeout_values.update(default_params)
 
-    def __init__(self, credentials, service=None, scope='project'):
+    def __init__(self, credentials, scope='project'):
         """Initialization of Manager class.
 
         Setup all services clients and make them available for tests cases.
         :param credentials: type Credentials or TestResources
-        :param service: Service name
         :param scope: default scope for tokens produced by the auth provider
         """
         _, identity_uri = get_auth_provider_class(credentials)
diff --git a/tempest/common/credentials_factory.py b/tempest/common/credentials_factory.py
index bf8d30e..e6b46ed 100644
--- a/tempest/common/credentials_factory.py
+++ b/tempest/common/credentials_factory.py
@@ -233,7 +233,6 @@
 class AdminManager(clients.Manager):
     """Manager that uses admin credentials for its managed client objects"""
 
-    def __init__(self, service=None):
+    def __init__(self):
         super(AdminManager, self).__init__(
-            credentials=get_configured_admin_credentials(),
-            service=service)
+            credentials=get_configured_admin_credentials())
diff --git a/tempest/test.py b/tempest/test.py
index 17dc94c..039afa1 100644
--- a/tempest/test.py
+++ b/tempest/test.py
@@ -219,7 +219,6 @@
     """
 
     setUpClassCalled = False
-    _service = None
 
     # NOTE(andreaf) credentials holds a list of the credentials to be allocated
     # at class setup time. Credential types can be 'primary', 'alt', 'admin' or
@@ -533,8 +532,7 @@
             else:
                 raise lib_exc.InvalidCredentials(
                     "Invalid credentials type %s" % credential_type)
-        manager = cls.client_manager(credentials=creds.credentials,
-                                     service=cls._service)
+        manager = cls.client_manager(credentials=creds.credentials)
         # NOTE(andreaf) Ensure credentials have user and project id fields.
         # It may not be the case when using pre-provisioned credentials.
         manager.auth_provider.set_auth()