On the side menu, select Campaigns, then select the campaign you no longer need and use the “delete” button.
Then you will be asked to confirm you want to delete your campaign. Make sure you really want to delete the campaign before confirming, as deleted campaigns can not be restored.
Once your campaign is deleted you will see a notification message.
Select Automations on the side menu and then at the bottom of the page select delete for the campaign and confirm that you would like this Automation to be deleted.