In Device Assignment, you can assign devices to users. It is accessible through the Users Panel on the Dashboard.

It shows you a complete list of all users created on your account and enables you to search users by applying different filters: email and Building. You may also tick the box next to Unassigned to only view the users with no device assigned.

It is possible to assign a device to a user by clicking the button. (it will be invisible until you move the mouse cursor over it) but it is also possible to open this list by clicking on the corresponding space in the Device column:

You can unassign a device by clicking the  button.