1. Go to Reports, Transaction Detail (or Journal Entries) and look up the particular entry posted.
2. Go to Reports, Inventory & services, Transactions and specify the date and the type of transactions.
3. Make note of the changes in the quantity and value of Adjustments/Transfers.
4. Post another inventory adjustment with opposite values and quantities to reverse the original entry.

You can now post another inventory adjustment with the desired changes if necessary.