Manually Unsubscribe a Contact from an Audience
Click on the Campaigns option in the left vertical content menu bar.
There are multiple methods to unsubscribe a contact; if you would like to unsubscribe from multiple audiences, the easiest method is to use the search feature.
Click on the Search Icon (magnifying glass icon, top right of page).
Type a search word(s) in the search box, and click on the Search button to find matching contacts across all your Audiences.
Select the contacts you would like to unsubscribe from by clicking on the check box to the left of the contacts you want to update (as shown below).
Click on the Action menu and select the option Unsubscribe.
Click on the Confirm button to commit your update, those contacts selected will now be marked as unsubscribed.