The Delete Group... menu item deletes one or more groups
  from a library.  The group must be empty, and also cannot
  belong to another group.

  When you choose Delete Group..., a dialog box appears,
  allowing you to specify options for the group you are
  deleting.

  To determine the elements and groups that belong to a
  specific group, do the following:

  1. Click on a group.
  2. Pull down the View menu.
  3. Choose the Expand submenu.
  4. Choose the Children item.

  To determine the elements and groups that belong to
  another group, do the following:

  1. Click on a group.
  2. Pull down the View menu.
  3. Choose the Expand submenu.
  4. Choose the Membership menu item.

1  –  Dg gedb

  The Delete Group dialog box allows you to enter
  information about the group or groups you want to delete
  from the library.

1.1  –  Dg gsf

  If you click on an object or objects before choosing
  the Delete Group... menu item, the Selected box contains
  those objects. CMS performs the delete transaction on the
  selected objects.

1.2  –  Dg gf

  Fill in the Group field with the name of one or more
  groups to be deleted.

  A group expression can be one or more group names, a
  wildcard expression, or a list of these separated by
  commas.

1.3  –  Dg grf

  Fill in the Remark field with text to be associated with
  the transaction and logged in the history file with this
  delete transaction.

1.4  –  Dg grcf

  Click on the Remove Contents button to indicate that CMS
  should remove elements and group members from the
  specified groups prior to deleting the groups.