[palosanto]

That's very strange that they aren't responding to the eraser - I'll have to see if I can reproduce that. In the meantime, open the layer window, select the annotation and then tap the trash can icon to delete the annotations.

That worked but, yeah, neither the select nor the erase tool respond ...

Mike, further to this problem where apparently I couldn't select or delete annotations that used to belong to a different page, today I did a similar exercise of inserting a new page and obviously the existing annotations of the next existing page ended up in the new page which makes sense.  However, because of the different cropping in the new or old page, the reason I couldn't erase or select the existing annotations is because they were now moved/stretched, however the select/delete tool keeps wanting to select the old location of the annotation.  So if I select the now empty area where the annotation used to be, the shifted/stretched annotation gets selected.
Does this make sense? 
Not sure if this has an easy programming solution where the existing annotations are able to match the new cropping and stretching of the inserted page and can then easily be selected or deleted.