Answer: When you deactivate a fund, Fundriver automatically creates transactions to zero out of the historical gift and market value for that fund.
What happens next to the balance depends on why you are closing the fund.
If you are transferring the balance out of the pool, then deactivating a fund just transfers the value out of the fund until the funds are physically removed from the investment. If this doesn't occur in the same posting period, you would need to account for the balance using Due To/Due From until the funds are removed from the investment.
If the intent is to transfer the balance to another fund, you will need to create transactions to do so (or otherwise your investment reconciliation will be off).