One thing is sure default accounts are mandatory you can change their names/codes according to your business need.
Secondly Why do you need this too lengthy chart of account when iDempiere can handle things smartly even with the available default accounts. So think thoroughly and make a smart chart of account (other things you can handle with dimensions like Products, Cost centers, Activity etc)
However to open these accounts please make a csv file and import in account element value tab.
rizwan anwar