Cannot remove the account from its primary group

User action:
Trying to remove the account from its primary group, at the user account's group membership page, at the Member of list box.

Meaning:
The primary group is a mandatory group for the user account. You cannot remove an account from its primary group.

Corrective action:
If you want to remove an account from its primary group, select the DCE UNIX Information page from the View or Modify field. At the Primary Group drop-down list, select another security group as the primary group. Then, go back to the group membership page to remove the old primary group from its Member of list.