Office Depot Chairman, CEO Nelson Resigns  NEW YORK (Reuters) - Office Depot Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=ODP.N target=/stocks/quickinfo/fullquote"&gt;ODP.N&lt;/A&gt; on Monday  said Chairman and Chief Executive Bruce Nelson has resigned  after the No. 2 U.S. office supply chain determined it needed a  new leader to boost sales and stem a slide in market share.