Several ways to remove/hide upload document from library

Hide/Disable Upload document  http://social.technet.microsoft.com/Forums/en-CA/sharepoint2010customization/thread/e40da66f-62dd-4927-ac47-91bcb68c342b

More on disabling upload http://www.endusersharepoint.com/STP/viewtopic.php?f=10&t=616

Simple hack in css http://www.patricktalmadge.com/2011/04/09/hide-multiple-upload-link-in-sharepoint-2010/