Specify the path to the credential file correctly.

automation/cleu-ansible-n9k/add_vlan.py

@@ -267,7 +267,7 @@ def main():
 
     p.poll()
 
-    if os.path.isfile(cred_file):
+    if os.path.isfile(cred_file.name):
         os.remove(cred_file.name)