Is there a way to lock down a project so that only certain users with certain roles can access?

The Roles tab within the Home project has an Available Projects column showing which projects can be opened by which roles.

Blank or "All" denotes the full list of projects can be seen by a logged-in user with that role type.

You can right-click and edit a role to control which projects they're allowed to open.

Thank you!!

Jenny,

One caveat that wasn't called out above. The Available Projects (and other permissions) can not be edited for Default Roles. If you are looking to edit the Available projects you will need to create new roles. (see below for warning in product)