Correct answer - "PurgeQueue" : Deletes the messages in a queue specified by the QueueURL
parameter.
Incorrect:
"DeleteQueue then CreateQueue" - When you delete a queue, the deletion process takes up to 60
seconds. Requests you send involving that queue during the 60 seconds might succeed.
"BatchDelete" - The command does not exist in the API
"ChangeVisibilityTimeout" - Changes the visibility timeout of a specified message in a queue to a
new value but does not delete all messages for you