A customer can belong to more than one group.
To configure the customer groups, navigate to Manager Home > Config > Customers > Customer Setup.
To activate groups, select "Yes" from the Use Customer Group Feature dropdown.
Add New Group:
To add a new group, click "Add New" from the Define Customer Groups dropdown.
A new window will appear. Name your new group and click Add.
The new group will appear in the dropdown list.
The customer groups will display on the customer profile on the front end as such.
The backend customer profile will display as such.
Now all purchase made by that customer will be linked to the group.
If for any reason you need to delete a group, select the group name from the drop down.
Click the "Delete" button.
You will be asked to confirm that you want to delete the group. Click OK and it will be deleted.
Be sure to always save your changes.