about Name Manager

Hello,

I always delete the name manager list (all of the list) and save all of my life.

But i wanna know is that correct? I mean what is inside of the name manager? how this list exist?

And the most important question: when i delete smtg in that list, is that broke smtg in file?

So I have a important file, it include so many things in list. In previous, I delete all the things for make my excel faster. What you can say and what is your advice about that?

Thank you.