can calibre remove all page breaks in document?

Hi I have three documents converted from a pdf with abbyy. They are odt, txt and rtf. Can calibre convert any of them to azw, or mobi and remove the page breaks from the original document. I think I did it once, but can't remember how. Heuristic proceessing may have done it.
Otherwise I may abandon my project, or just create an ebook with gaps allover the place. The original pdf is 400 pages long and I don't want to do it by hand!

Any help appreciated. ;););)