The Unsubscribe link cannot be removed from the footer of the emails that you send using Email Broadcast/Sequences/Workflows/Automations as it is mandatory to have an Unsubscribe link on all the marketing emails as per marketing guidelines. However, you can remove that from One-One emails

To remove it from One-One Emails, Please click the profile picture on the top right and select Account Settings-->Domain Settings, click on the Other tab and you will find the option. Please uncheck "Show Unsubscribe link" under One-One emails.