As long as the scheduled send time of your email has not passed, you can delete an email from within your automation.
Navigate to Email Center → Email Automation from the top menu
Click the name of the automation that contains the email you'd like to delete.
Click the "Delete" icon next to the email you'd like to delete.
Deleting an email cannot be undone. There is no way to recover the email once it has been deleted.
Check the box that you understand that deleting the email is permanent and click "Delete Email"