Double Title Header in ebook

[Kawasaki]

I've just joined this site today and hope you can help.

I uploaded a docx file I compiled on Scrivener to Kindle and now it's live on Amazon. When I checked it out, to my horror, I saw I'd doubled a title appearing on the ToC page and also on its own page in the text body:

Part One: PART 1: Deceptively Your
(See attached screen shot)

I followed Kindle's instructions about downloading the file for revising. While it's easy to revise the text, I couldn't figure out how to change the ToC using Word on my Mac.

I'm not conversant with html, but I wonder if I can use Calibre to delete the first "Part One," If so, please direct me to where I can learn how to do this, or perhaps someone could tell me by way of this post if the procedure is not too difficult.

Thank you.