A year later -- I know this is an old post, but I just joined the forum after stumbling over this.
Open the page in a text editor, such as notepad.
There should be a line at the top, something like:
<!-- InstanceBegin template="/Templates/TemplateName.dwt" codeOutsideHTMLIsLocked="true" -->
Change the true to false, or if you dont want to use the template, remove the line altogether.