If your inbox is cluttered with conversations or email threads you don't need to be part of, use Ignore to delete the emails and any new emails that are added to the conversation.
Select the conversation or an email in the thread.
Select Ignore Conversation.
Note: The Ignore Conversation command in step 3 appears in the Ignore Conversation dialog box. This dialog box doesn’t appear if you previously selected the Don’t show this message again check box.