It has totaly stuffed up the whole first page which I can neither edit, delete or loginto. I have an alternative way to login and edit

Hi Thanks for responding
 

The situation is that even when I deselect that option I cannot delete or edit the page where the source was originally placed

you should be able to remove a module from a page in layout mode (where content is not rendered).

if a page is unaccessible, you can edit settings and delete it from inside Admin :: pages menu item.

Please don't crosspost same question in multiple forums.