I found was that it is apparently impossible to delete entries once they have been added to the Beginning Balances grid under Administration, even if added through the front end. Although there are several API methods provided to delete rows, and the rows do disappear, upon reopening the form they are still there, although most of the data has been deleted, the account numbers for all previously deleted rows is still present. The second thing, is that I cannot figure out where in the database those account numbers are coming from. I manually delete the rows from the GLSummary table and the accounts numbers still show up.
The account numbers which appear in the beginning balances grid are stored in the GL7ACCOUNTS table.
All account numbers grouped by funds will be listed in the Beginning Balances grid. Only when the fund’s beginning balances are locked, will they be excluded from the grid. By default the balances are zero and can be updated manually or through the API. You can clear the balances but the account numbers/class associated with each fund will continue to be listed. The only way to remove the account from the list would be to delete that account.