While KnowledgeTree recommends using page layout assignments as a means of providing access to certain groups of users, we understand that this method may not be the most feasible for all.
Salesforce Administrators can also easily restrict access to KnowledgeTree for Salesforce through the use of profiles.
Go to Setup -> Manage Users -> Profiles
Select the Profile you wish to edit by clicking on the profile name, NOT the edit button.
At the top of the page, click on "Enabled Visualforce Page Access".
Then click on Edit.
Finally, highlight all Enable Visualforce Pages in the right column that contain the "ktree" prefix and click the Remove arrow to disable them. Click Save.
Repeat this for any other profiles in which you wish to limit KnowledgeTree access.