There may be a pretty straight forward answer to this question, but I have to ask, just to make absolutely sure. 

Question; do we have to keep the default structure of the pre configured product categories? 

i.e. 

All 

All/Deliveries

All/Expenses

All/Saleable

All/Saleable/POS

etc...

Or can we simply just name our own categories with our own structure? 

i.e.

Vitamins

Supplements

Sports Drinks

Raw Ingredients

Flavoring

Coloring

Containers & Packaging

etc... 

And is it suitable to use our own categories without a parent category, as with the defaults? 

I'm sorry if this is a fairly silly questions, but since I am still trying to learn Odoo, I want to makes sure I am not changing a default that Odoo requires to run seemlesly.

Thank you in advance, 

Chris

Edited: to correct typos