If you are able to join a group in your course, you can leave the group at any time. You cannot leave groups that are not self sign-up groups.
When a course is concluded, all associated groups will be shown as previous groups in your groups list.
In Course Navigation, click the People link.
Click the Groups tab.
You can also access your User Groups through the Settings menu. Click the Options icon  and click the View User Groups link .
Next to the name of an available group, click the Leave link.
A message appears at the top of your browser verifying you left the group.