Hi Daniel,
I am not sure if this will help, but give it a try. When building forms, the root subform sometimes gets too large and a blank page gets generated (particurarly with tables). Similar to your form, it is not possible to delete this new page.
What works for me is to select the root subform and reduce its size manually, by dragging the bottom right corner back into the page. It will reduce to the objects in the subform and (hopefully) the extra page will be gone, never to return! Wha ha ha!
Good luck,
Niall