Many of the tasks we used to do under assignments last year has moved to the settings panel in your gradebook. Here is a screencast to walk you through all of the options and what does what. You can find this and other resources about the gradebook within Campus Instruction Beta by clicking here.
I had a teacher ask me if there was a way to hide or remove students who are no longer in your class. The answer is maybe. It depends on if they are officially dropped from your class and appearing as red in your roster and gradebook. If not, then no, you cannot remove them until they have been unenrolled from the class. If the student is showing up as red in your gradebook though, you can hide them so you don't have to worry about them. Here is a screenshot to help you do it: