1. To categorize your projects, click “Projects” from the left hand navigation bar
  2. Click on the small gear icon next to “Create Project” on the top right and select “Mange Categories”
    1 
  3. In the Manage Categories window, select “+New Category”
    1
  4. Since you can only have one category tree, create a category structure that can describe all the projects in your domain.
    1

Unassign a category from a group/project can be done from the same window.