It may just be a bug in the template drop-down menu code. This is the normal method:
Put all the templates in Context X into a category called ContextXTemplates
Put all the users who should see those templates in a user group called ContextXUsers
In Security -> Access Controls, Right-click on the ContextXUsers group and select Update User Group.
On the Element Category tab, click on "Add Category" and enter the following settings:
Category: ContextXTemplates
Minimum Role: Whatever the role the user's have
Access Policy: Element
Context: mgr
Click on the "Save" button in the dialog.
Click on the "Save" button at the upper right.
That should hide those templates from any user not in the group (including you, unless you add yourself to the user group).
---------------------------------------------------------------------------------------------------------------
PLEASE, PLEASE specify the version of MODX you are using . . . PLEASE!
MODX info for everyone:
http://bobsguides.com/modx.html