Is it mandatory to create Cash Account Ledger in Tally.ERP 9?

In Tally.ERP 9 we can create Ledgers using Ledger Creation screen. It having some default ledgers which are already created by the Accounting Software itself. And Cash ledger is one of them.

So, you do not need to create the Cash Ledger in Tally software. If you open List of Ledgers screen you can find out that the Cash Ledger can be found under Cash-in-hand predefined Accounting Group.

So, you do not need to create the Cash Ledger and use the existing ledger. If you want to create any other ledger which is having the similar nature of Cash you can create it under Cash-in-hand Groups.