To delete a person added to a schedule page, simply go to "Edit" on the schedule item and hit the "x" next to the person you want to delete. It will only delete the person from this page - not from other pages it is attached to.
A schedule item has two ⋯ menus, and they do different things:
The one next to a person acts on that person — for example, editing their profile.
The one in a list's header acts on the whole list, and that's where Delete list lives.
So if you want to take one person off a session, use the "x" next to them. If you want the whole group gone, delete the list instead. Either way, nobody is deleted from your app — they stay on your People pages and on any other sessions they're attached to.
Related articles that might be helpful:
Start with the guide to lists on schedule items
See how you can delete a whole list of people
See how you can attach people to schedule items