You can also add and remove users to specific projects that they're to manage.
To do so, simply navigate to the project you would like to add a user to and choose the 'members' option from the drop down in the top right then choosing the 'Add Member' option.
From there you can either type out the users name, or email address associated with their account and you can add them to that project.
To remove a user from a project, simply navigate to the same members area and click on the person you want to remove. Once you click on their name an option to remove them will appear.