The presentation is public, so anyone is allowed to view it. You can make the presentation private if you want only certain users to be able to view it.

The following users may view the presentation: (or you can make the presentation public so everyone can view it)		No users. @read_users.first_names@ @read_users.last_name@ (creator) [remove]
The following users may view and make changes to the presentation:		No users. @write_users.first_names@ @write_users.last_name@ (creator) [remove]
The following users may view and make changes to the presentation, and decide who gets to view/edit it:		No users. @admin_users.first_names@ @admin_users.last_name@ (creator) [remove]