As an admin user, you can restrict the calendar access of all other users.
Start at the “User Management” page
Under User tab, either select the current user and click “edit”, or click “add” to add a user.
Add the basic information for the user
Click “Settings (Role and Restrictions)”, to show the various options
Click the third check box next to “Restrict Calendar Visibility”
After clicking the box, you have the option adjust which users are restricted or allowed.
To allow access, select the user from the left column, and click the > arrow to move to the allowed column.
To restrict, select a user from the right column and click the < arrow to move to the restricted column.
Once the requested information is filled in, click save.