In order to do this, you need to modify the portal-ext.properties file located in..
Note that it is possible that you may not have permissions to modify this file if you are running a hosted environment (Nimsoft On Demand).
If that is the case, bring this to the attention of Nimsoft Support for assistance.
Modify or add the following lines anywhere in the file (typically at the end of the file)...
This will remove the link to Private Pages and Public Pages on the Docking Bar and you will only see the communities that the users have access to.
If you want to remove one or the other, then you can easily do so by only modifying the appropriate entry.
For example, if you only want users to see Public Pages, you can configure as follows...