There are two ways to prevent students from accessing a course, usually the first method is used.
1) 'Others > Course Settings'
Set 'Enable classroom' to 'No' in 'Others > Course Settings' on the left menu of 'Course room'.
If set to 'No', it will be displayed in the student course list, but you will not be able to enter the 'Course room'.
Set to ‘보기설정 - Hide’ in ‘Advanced course management > Edit settings’on the left menu of ‘Course room’.
(Caution) If set to ‘Hide’, both the instructor and students are not displayed in the course list. If you would like to set 'Enable classroom' to 'Show' again, please contact the school/institutional administrator.