"Group By" Box

Our accountant called me up to his office today, he has a box above his messages windows and next to his outlook shortcut bar. The box is labeled Group By and he wants it gone, he does not know how it arrived there. Appently what this allows you to do is drop one of the columns (subject, sent by, date.....) up into the "group by" box and outlook will then change its view to only show for example subjects with the plus sign next to them, so all e-mails that begin with the same subject will be put in their own group. I cannot figure how to get rid of this. I haven't found it in help, Microsoft KB, google, and yahoo. Can find references to it but now how to close it <IMG SRC="smilies/confused.gif" border="0"> <IMG SRC="smilies/confused.gif" border="0"> .

Please help me get rid of this annoying box,
Tony