All contributors and viewers for an organization can automatically access every team project. Contributors can only access a private project if they have been invited. Project administrators have the permission to add and remove people from private projects.
From the project dashboard:
- Select the project you'd like to manage.
- Click Members from the left-hand navigation.
- Use the ••• menu from the upper-right corner of the member card.
- Select Remove from project... to remove them from the project.
Adding a viewer to a specific project will only grant that person access to that project. That viewer will not have access to all projects in your organization. You can invite viewers to your organization to give them access to all team projects.