To close a fiscal year, create a Period Closing Voucher, set:
- Posting date: end of year
- Closing account head: 3210.000 Laba Ditahan

Save then Submit. In theory, this will zero out all income and expense accounts.
However, there is a bug: frappe/erpnext #25572 . Hendy has sent a PR.
Which means: you need to check account balances manually (you can use Profit/Loss Statement Report) and if there are still accounts with non-zero balance, you add adjustment journal entry manually to correct for Period Closing Voucher’s journal entry.