You can hide triggered messages that you don’t want to be sending or viewing the statistics of which any longer. To do this, pick the messages you want to archive in the Triggered messages section. The "Archive" button will appear in the top bar:

Or click the “Archive message” button next to the message you want to remove:

This way, you’ll hide the triggered message from the list. You will be able to find it in the “Archived messages” folder: