When you delete a "Send Email" action from an automation, the automated campaign in the action will not be deleted. Only the action itself.
To see emails not currently being used in an automation, click the arrow (<< icon) located on the top right of the automation builder to open the Settings and Messages drawer. Then click the “Messages” tab.
Any emails not in a “Send Email” action will have a yellow exclamation point to the left of the email name.
If you hover over the icon, it will state, “This email is not currently being used in this automation.”
In addition, clicking "Automation Messages" on the Automations overview page will list every automated campaign created for your automation, whether or not they are in use.
Learn how to delete an automated campaign from your account.