I am sure it's been blogged tons o' times already, but it's the first thing that came up when I MSN'd it http://search.msn.com/results.aspx?q=rtm+visual+studio+beta+uninstall&FORM=QBHP.  These instructions should help http://lab.msdn.microsoft.com/vs2005/uninstall/preRTMuninstall/default.aspx.  Don't miss the auto-uninstall tool at the top of the page.

-Marc