"Main Body" - can this be changed?

In my TOC I always see a section called Main Body, set apart by a Roman numeral I. It’s not applicable to the type of book I’m working on, and I’d like to change the words or eliminate it entirely.

I also would like to understand what it signifies. There is no similar section in the TOC for other sections, such as Front Matter and Back Matter (which is good, I would not want them). But since Main Body has a I in front of it, I would assume there might be a II, III, IV, etc., but I can’t figure out what/where they are. I thought it might be the default title of a “Part” but I created a Part and it had no effect.

Thanks in advance!

I stumbled upon the answer to this, so I’m sharing in case anyone else is trying to figure it out. “Main Body” is basically the default “Part” that holds everything. After creating a new “Part”, my chapters have the option to select which Part they belong to, and the list includes “Main Body” and my newly-named “Part One” (which of course I can change to whatever I want).

Furthermore, the title “Main Body” can be changed as I had originally hoped. Go to “Organize” hover over Main Body, and click Edit.

Thank you so much for the contribution. I had the same question yesterday while rewriting a textbook - for the 4th time. Obviously I am learning from errors and now help from a Community.