You can delete any of your custom email templates if you no longer need them. However, you cannot delete any of the 8 default email templates from the system.
- Go to Settings > Emails
- Click on the name of the email template you'd like to delete to expand it
- Click the "Delete" link at the top right corner of the email
- Click "OK" on the confirmation message that pops up to confirm that you'd like to delete it