Nike Co-Founder Knight Steps Down as CEO  SAN FRANCISCO (Reuters) - Philip Knight, the co-founder of  Nike Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=NKE.N target=/stocks/quickinfo/fullquote"&gt;NKE.N&lt;/A&gt;, is stepping down as chief executive officer,  the athletic shoe company said on Thursday.