When creating (or editing) a curriculum, you may define some of the courses as optional. Setting some of the courses as optional means that learners do not have to take these courses to complete the curriculum and get awarded the certificate (in the case where the curriculum awards a certificate upon completion).
In order to do so, log in as administrator and from your Administration dashboard visit the curricula section, then click to edit the curriculum. Next, move to the Courses tab, which contains a list of all courses available in your system that indicates which of them belong to that specific curriculum.
Toggle the corresponding handler in the column Optional (1) to set a course as optional for this curriculum or not.