You can hide the Subscribe to all button in your Event Collection settings. If you turn off the subscribe option, your public collection page will only offer individual event additions.
To disable this button, edit the event collection and disable the "Show 'Add to calendar' button" toggle.
Important: You do not need a collection to let people add a single event to their calendar. Collections are only needed if you want people to subscribe to a calendar and automatically receive updates and new events.
Individual Add to Calendar buttons
The Event Collection page does not support an Add to Calendar button next to each event in the list. Those buttons only appear on each event's own page. Alternatively, you can place direct Add-to-Calendar links on your own website or in an email.
Subscriptions vs. individual additions
When someone subscribes to a collection, it shows as a +1 in your event collection subscriber count.
If registration is not required, users can click Subscribe to all to subscribe to all future events without filling out an RSVP form. You can still track active subscribers and views, but you will not have detailed attendee information for each event.