With CollaborNation you can easily remove or move people from one Reporting Group to another. To do so, go to Reporting Groups and select a group with learners. Then under Group Members click on Edit.
On this page you will see the Current Group Members included in the group. Simply select the people you'd like to move, then under the "Select an action" dropdown you can either remove them from the current group or move them to another group. When you're finished click on Save Changes.