You can either delete an entire conversation thread or one specific message from a conversation.

To delete an entire conversation thread:

1. Open the message (or select the checkbox next to it).
2. Click the Delete button. 
   

To delete a single message from a conversation thread:

1. Open the conversation and find the message.
2. Click the down arrow next to Reply, at the top right of the message pane.
   
3. Click Delete this message.

Doing this will move the conversation thread or message to your Trash, which can be found on the left side of your Gmail page. (If you don't see Trash along the left side of your Gmail page, click the More drop-down menu at the bottom of your label list.)

Items in your Trash will remain there for approximately 30 days before it is automatically emptied and permanently deleted*.

If you’d like to permanently delete something yourself:

1. Click your Trash label.
2. Check the box next to the message you'd like to permanently delete.
3. Click the Delete forever button.

How do I get something out of Trash?

You can retrieve something from Trash by clicking Trash, selecting the message in question, and clicking Inbox in the 'Move to' drop-down menu. Items that are permanently deleted can’t be retrieved.

*Please be aware, residual copies of deleted messages and accounts may take up to 60 days to be deleted from our active servers and may remain in our backup systems for an additional period of time.