There are two ways to customize or modify your course with pre-assessments: the NROC Course Manager or your LMS.
The NROC Course Manager has an interface that allows you to hide topics within a unit. These topics will not be covered when a student takes the pre-assessment.
Your LMS has features for hiding or rearranging whole units. Since the topics in the pre-assessments are not broken out and available as individual topics, there is no way to manage individual topics in the LMS. (Control over individual topics at the LMS level is available in the standard version of Developmental Math, without PreAssessments.
There is no feature in the NROC Course Manager to hide an entire Unit in the LMS. Even if you hide all the topics in a Unit via the NROC Course Manager, it will not affect the LMS display. Your students will still see the Unit Map, Quizzes, Learning Objectives, etc. Use the LMS features to hide those units or other items you do not wish students to interact with at all.