You can only delete an automation if no emails have been sent within the automation.
Once an email has been sent, you can stop the automation but deleting is no longer possible.
Get started
Navigate to Email Center → Email Automation from the top menu
Press the "Delete Automation" icon next to the automation you want to delete.
Confirm you understand what you are deleting, check the box and click the "Delete Automation" button
Your automation is deleted