The answer is yes. There are settings in your control center that will allow you to deny access to everyone but yourself.
In your security settings select YES I WANT CONTROL. That setting requires anyone who attempts to access your appointment book to apply for access. If it ever happens that someone does apply then simply deny and ignore their request.
If you feel that you need more security then go to the page COLUMN NAMES in your control center and check each named column. This will hide all columns in the appointment book from everyone but you and your assigned managers.
Test your security by getting an additional client membership and try logging in and viewing your own appointment book. As a client you simply will not see it.
