To change or remove a users group do the following:
On the Users tab click on the magnifying glass next to the user you want to manage. This will bring up the manage window.
Next click the Edit icon. This will then open the edit window for this user.
To change or remove the users group. Highlight the current group and delete the entry using the backspace or delete key on your keyboard. Doing this will generate the entire list of groups.
To change the user to a different group select the new group from the list then click the OK button.
To remove the user from the group leave the "group" field blank the click OK.