Dear Ms. Aimee
Unit accounts have a balance that is brought forward when the year is closed. Unfortunately, There is no way from within the application layer of Great Plains that you can clear the beginning balance for a unit account.
The solution is to consider Database solution, using SQL Management Studio. For more information, please refer to MS Knowledge base article No. 857582 " How to clear beginning balances for unit accounts in General Ledger in Microsoft Dynamics GP"
Best Regards,
Mahmoud AlSaadi