This feature is activated by logging into your admin area and heading over to the appointments or services page. Once here, you need to click on the 'edit' icon indicated by a pencil as follows:
This will now enter 'edit' mode for that particular offering. Scroll down until you reach the section (screenshot to follow) where you will need to click the checkbox if you wish to hide the service, or, uncheck the checkbox to display the service.
Hide means your appointment or service won't show up on your main booking page. You will need to share the link for someone to book you using it.
Click the SAVE button and this particular service will now either be hidden or displayed on your page depending on whether the checkbox is activated or not.
Hope that answers your question!