There are two ways people can be removed from groups.
Removing from Within Group
To remove a person from a group, simply view the group in the Admin Area. From there, click the checkbox to the left of the person you’d like to remove. Then click the ‘Mass Manage’ button as pictured below.
A mass manage modal will appear, select ‘Remove from Group’ and click ‘Perform Mass Manage’.
Remove from Person’s Profile
View the person’s profile and on the left-hand side, click the delete button next to the group.